rtos: declare local symbols as static

Functions and variables that are not used outside the file should
be declared as static.

Change-Id: I9731a35496cd1c7421563c8961da5fa0e3cc71c3
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/5894
Tested-by: jenkins
Reviewed-by: Jonathan McDowell <noodles-openocd@earth.li>

src/rtos/nuttx.c

@@ -72,7 +72,7 @@ struct tcb {
 	uint8_t  dat[512];
 };
 
-struct {
+static struct {
 	uint32_t addr;
 	uint32_t prio;
 } g_tasklist[TASK_QUEUE_NUM];