output: Constify module options.

src/libsigrok-internal.h

@@ -205,11 +205,8 @@ struct sr_output_module {
 	/**
 	 * Returns a NULL-terminated list of options this module can take.
 	 * Can be NULL, if the module has no options.
-	 *
-	 * If cached is TRUE, no new GVariants are created for the def and
-	 * values fields; instead, the current values are returned.
 	 */
-	struct sr_option *(*options) (void);
+	const struct sr_option *(*options) (void);
 
 	/**
 	 * This function is called once, at the beginning of an output stream.

src/output/ascii.c

@@ -238,7 +238,7 @@ static struct sr_option options[] = {
 	{ 0 }
 };
 
-static struct sr_option *get_options(void)
+static const struct sr_option *get_options(void)
 {
 	if (!options[0].def) {
 		options[0].def = g_variant_new_uint32(DEFAULT_SAMPLES_PER_LINE);

src/output/bits.c

@@ -224,7 +224,7 @@ static struct sr_option options[] = {
 	{ 0 }
 };
 
-static struct sr_option *get_options(void)
+static const struct sr_option *get_options(void)
 {
 	if (!options[0].def) {
 		options[0].def = g_variant_new_uint32(DEFAULT_SAMPLES_PER_LINE);

src/output/hex.c

@@ -238,7 +238,7 @@ static struct sr_option options[] = {
 	{ 0 }
 };
 
-static struct sr_option *get_options(void)
+static const struct sr_option *get_options(void)
 {
 	if (!options[0].def) {
 		options[0].def = g_variant_new_uint32(DEFAULT_SAMPLES_PER_LINE);

src/output/output.c

@@ -225,7 +225,7 @@ SR_API const struct sr_output *sr_output_new(const struct sr_output_module *o,
 		GHashTable *options, const struct sr_dev_inst *sdi)
 {
 	struct sr_output *op;
-	struct sr_option *mod_opts;
+	const struct sr_option *mod_opts;
 	const GVariantType *gvt;
 	GHashTable *new_opts;
 	GHashTableIter iter;

src/output/wav.c

@@ -339,7 +339,7 @@ static struct sr_option options[] = {
 	{ 0 }
 };
 
-static struct sr_option *get_options(void)
+static const struct sr_option *get_options(void)
 {
 	if (!options[0].def)
 		options[0].def = g_variant_ref_sink(g_variant_new_double(0.0));