Fix #145

Don't tc_printf in the probe.
tc_printf fixed to not crash of no controller connected.

src/target/stm32f1.c

@@ -165,7 +165,6 @@ bool stm32f1_probe(target *t)
 	}
 
 	flash_size = (target_mem_read32(t, FLASHSIZE_F0) & 0xffff) *0x400;
-	tc_printf(t, "flash size %d block_size %d\n", flash_size, block_size);
 	target_add_ram(t, 0x20000000, 0x5000);
 	stm32f1_add_flash(t, 0x8000000, flash_size, block_size);
 	target_add_commands(t, stm32f1_cmd_list, "STM32F0");

src/target/target.c

@@ -446,6 +446,10 @@ void tc_printf(target *t, const char *fmt, ...)
 {
 	(void)t;
 	va_list ap;
+
+	if (t->tc == NULL)
+		return;
+
 	va_start(ap, fmt);
 	t->tc->printf(t->tc, fmt, ap);
 	va_end(ap);