Fix various gcc 8 compiler warnings related to ARRAY_SIZE.

Example:

  In file included from src/hardware/kecheng-kc-330b/protocol.h:26,
                   from src/hardware/kecheng-kc-330b/api.c:22:
  src/hardware/kecheng-kc-330b/api.c: In function ‘config_list’:
  src/libsigrok-internal.h:51:34: warning: division ‘sizeof (void *) / sizeof (void)’ does not compute the number of array elements [-Wsizeof-pointer-div]
   #define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
                                    ^
  src/libsigrok-internal.h:55:32: note: in expansion of macro ‘ARRAY_SIZE’
   #define ARRAY_AND_SIZE(a) (a), ARRAY_SIZE(a)
                                  ^~~~~~~~~~
  src/libsigrok-internal.h:964:43: note: in expansion of macro ‘ARRAY_AND_SIZE’
    std_opts_config_list(key, data, sdi, cg, ARRAY_AND_SIZE(scanopts), \
                                             ^~~~~~~~~~~~~~
  src/hardware/kecheng-kc-330b/api.c:296:10: note: in expansion of macro ‘STD_CONFIG_LIST’
     return STD_CONFIG_LIST(key, data, sdi, cg, NULL, drvopts, devopts);
            ^~~~~~~~~~~~~~~

src/hardware/asix-sigma/api.c

@@ -226,7 +226,7 @@ static int config_list(uint32_t key, GVariant **data,
 {
 	switch (key) {
 	case SR_CONF_DEVICE_OPTIONS:
-		return STD_CONFIG_LIST(key, data, sdi, cg, NULL, drvopts, devopts);
+		return STD_CONFIG_LIST(key, data, sdi, cg, NO_OPTS, drvopts, devopts);
 	case SR_CONF_SAMPLERATE:
 		*data = std_gvar_samplerates(samplerates, samplerates_count);
 		break;

src/hardware/baylibre-acme/api.c

@@ -216,7 +216,7 @@ static int config_list(uint32_t key, GVariant **data,
 	if (!cg) {
 		switch (key) {
 		case SR_CONF_DEVICE_OPTIONS:
-			return STD_CONFIG_LIST(key, data, sdi, cg, NULL, drvopts, devopts);
+			return STD_CONFIG_LIST(key, data, sdi, cg, NO_OPTS, drvopts, devopts);
 		case SR_CONF_SAMPLERATE:
 			*data = std_gvar_samplerates_steps(ARRAY_AND_SIZE(samplerates));
 			break;

src/hardware/hung-chang-dso-2100/api.c

@@ -490,10 +490,10 @@ static int config_list(uint32_t key, GVariant **data,
 
 	switch (key) {
 	case SR_CONF_SCAN_OPTIONS:
-		return STD_CONFIG_LIST(key, data, sdi, cg, scanopts, NULL, NULL);
+		return STD_CONFIG_LIST(key, data, sdi, cg, scanopts, NO_OPTS, NO_OPTS);
 	case SR_CONF_DEVICE_OPTIONS:
 		if (!cg)
-			return STD_CONFIG_LIST(key, data, sdi, cg, NULL, drvopts, devopts);
+			return STD_CONFIG_LIST(key, data, sdi, cg, NO_OPTS, drvopts, devopts);
 		*data = std_gvar_array_u32(ARRAY_AND_SIZE(devopts_cg));
 		break;
 	case SR_CONF_SAMPLERATE:

src/hardware/ikalogic-scanalogic2/api.c

@@ -299,7 +299,7 @@ static int config_list(uint32_t key, GVariant **data,
 {
 	switch (key) {
 	case SR_CONF_DEVICE_OPTIONS:
-		return STD_CONFIG_LIST(key, data, sdi, cg, NULL, drvopts, devopts);
+		return STD_CONFIG_LIST(key, data, sdi, cg, NO_OPTS, drvopts, devopts);
 	case SR_CONF_SAMPLERATE:
 		*data = std_gvar_samplerates(ARRAY_AND_SIZE(sl2_samplerates));
 		break;

src/hardware/ikalogic-scanaplus/api.c

@@ -253,7 +253,7 @@ static int config_list(uint32_t key, GVariant **data,
 {
 	switch (key) {
 	case SR_CONF_DEVICE_OPTIONS:
-		return STD_CONFIG_LIST(key, data, sdi, cg, NULL, drvopts, devopts);
+		return STD_CONFIG_LIST(key, data, sdi, cg, NO_OPTS, drvopts, devopts);
 	case SR_CONF_SAMPLERATE:
 		*data = std_gvar_samplerates(ARRAY_AND_SIZE(samplerates));
 		break;

src/hardware/kecheng-kc-330b/api.c

@@ -293,7 +293,7 @@ static int config_list(uint32_t key, GVariant **data,
 {
 	switch (key) {
 	case SR_CONF_DEVICE_OPTIONS:
-		return STD_CONFIG_LIST(key, data, sdi, cg, NULL, drvopts, devopts);
+		return STD_CONFIG_LIST(key, data, sdi, cg, NO_OPTS, drvopts, devopts);
 	case SR_CONF_SAMPLE_INTERVAL:
 		*data = std_gvar_tuple_array(ARRAY_AND_SIZE(kecheng_kc_330b_sample_intervals));
 		break;

src/hardware/lecroy-logicstudio/api.c

@@ -410,7 +410,7 @@ static int config_list(uint32_t key, GVariant **data,
 {
 	switch (key) {
 	case SR_CONF_DEVICE_OPTIONS:
-		return STD_CONFIG_LIST(key, data, sdi, cg, NULL, drvopts, devopts);
+		return STD_CONFIG_LIST(key, data, sdi, cg, NO_OPTS, drvopts, devopts);
 	case SR_CONF_SAMPLERATE:
 		*data = std_gvar_samplerates(ARRAY_AND_SIZE(samplerates));
 		break;

src/hardware/lecroy-xstream/api.c

@@ -315,10 +315,10 @@ static int config_list(uint32_t key, GVariant **data,
 
 	switch (key) {
 	case SR_CONF_SCAN_OPTIONS:
-		return STD_CONFIG_LIST(key, data, sdi, cg, scanopts, NULL, NULL);
+		return STD_CONFIG_LIST(key, data, sdi, cg, scanopts, NO_OPTS, NO_OPTS);
 	case SR_CONF_DEVICE_OPTIONS:
 		if (!cg)
-			return STD_CONFIG_LIST(key, data, sdi, cg, NULL, drvopts, devopts);
+			return STD_CONFIG_LIST(key, data, sdi, cg, NO_OPTS, drvopts, devopts);
 		*data = std_gvar_array_u32(ARRAY_AND_SIZE(devopts_cg_analog));
 		break;
 	case SR_CONF_COUPLING:

src/hardware/link-mso19/api.c

@@ -284,7 +284,7 @@ static int config_list(int key, GVariant **data,
 {
 	switch (key) {
 	case SR_CONF_DEVICE_OPTIONS:
-		return STD_CONFIG_LIST(key, data, sdi, cg, NULL, drvopts, devopts);
+		return STD_CONFIG_LIST(key, data, sdi, cg, NO_OPTS, drvopts, devopts);
 	case SR_CONF_SAMPLERATE:
 		*data = std_gvar_samplerates_steps(ARRAY_AND_SIZE(samplerates));
 		break;

src/hardware/pipistrello-ols/api.c

@@ -325,7 +325,7 @@ static int config_list(uint32_t key, GVariant **data,
 
 	switch (key) {
 	case SR_CONF_DEVICE_OPTIONS:
-		return STD_CONFIG_LIST(key, data, sdi, cg, NULL, drvopts, devopts);
+		return STD_CONFIG_LIST(key, data, sdi, cg, NO_OPTS, drvopts, devopts);
 	case SR_CONF_SAMPLERATE:
 		*data = std_gvar_samplerates_steps(ARRAY_AND_SIZE(samplerates));
 		break;

src/hardware/zeroplus-logic-cube/api.c

@@ -395,7 +395,7 @@ static int config_list(uint32_t key, GVariant **data,
 
 	switch (key) {
 	case SR_CONF_DEVICE_OPTIONS:
-		return STD_CONFIG_LIST(key, data, sdi, cg, NULL, drvopts, devopts);
+		return STD_CONFIG_LIST(key, data, sdi, cg, NO_OPTS, drvopts, devopts);
 	case SR_CONF_SAMPLERATE:
 		devc = sdi->priv;
 		if (devc->prof->max_sampling_freq == 100)

src/libsigrok-internal.h

@@ -960,6 +960,8 @@ SR_PRIV int std_opts_config_list(uint32_t key, GVariant **data,
 	const uint32_t scanopts[], size_t scansize, const uint32_t drvopts[],
 	size_t drvsize, const uint32_t devopts[], size_t devsize);
 
+extern SR_PRIV const uint32_t NO_OPTS[1];
+
 #define STD_CONFIG_LIST(key, data, sdi, cg, scanopts, drvopts, devopts) \
 	std_opts_config_list(key, data, sdi, cg, ARRAY_AND_SIZE(scanopts), \
 		ARRAY_AND_SIZE(drvopts), ARRAY_AND_SIZE(devopts))

src/session_driver.c

@@ -328,7 +328,7 @@ static int config_set(uint32_t key, GVariant *data,
 static int config_list(uint32_t key, GVariant **data,
 	const struct sr_dev_inst *sdi, const struct sr_channel_group *cg)
 {
-	return STD_CONFIG_LIST(key, data, sdi, cg, NULL, NULL, devopts);
+	return STD_CONFIG_LIST(key, data, sdi, cg, NO_OPTS, NO_OPTS, devopts);
 }
 
 static int dev_acquisition_start(const struct sr_dev_inst *sdi)

src/std.c

@@ -39,6 +39,8 @@
 
 #define LOG_PREFIX "std"
 
+SR_PRIV const uint32_t NO_OPTS[1] = {};
+
 /**
  * Standard driver init() callback API helper.
  *
@@ -581,7 +583,7 @@ SR_PRIV int std_opts_config_list(uint32_t key, GVariant **data,
 	switch (key) {
 	case SR_CONF_SCAN_OPTIONS:
 		/* Always return scanopts, regardless of sdi or cg. */
-		if (!scanopts)
+		if (!scanopts || scanopts == NO_OPTS)
 			return SR_ERR_ARG;
 		*data = g_variant_new_fixed_array(G_VARIANT_TYPE_UINT32,
 			scanopts, scansize, sizeof(uint32_t));
@@ -589,13 +591,13 @@ SR_PRIV int std_opts_config_list(uint32_t key, GVariant **data,
 	case SR_CONF_DEVICE_OPTIONS:
 		if (!sdi) {
 			/* sdi == NULL: return drvopts. */
-			if (!drvopts)
+			if (!drvopts || drvopts == NO_OPTS)
 				return SR_ERR_ARG;
 			*data = g_variant_new_fixed_array(G_VARIANT_TYPE_UINT32,
 				drvopts, drvsize, sizeof(uint32_t));
 		} else if (sdi && !cg) {
 			/* sdi != NULL, cg == NULL: return devopts. */
-			if (!devopts)
+			if (!devopts || devopts == NO_OPTS)
 				return SR_ERR_ARG;
 			*data = g_variant_new_fixed_array(G_VARIANT_TYPE_UINT32,
 				devopts, devsize, sizeof(uint32_t));