Add MBED_CONF_APP_TIMER/IDLE_THREAD_STACK_SIZE to configure timer/idle thread stack size by application

Author: ccli8

rtos/TARGET_CORTEX/mbed_rtx_conf.h

@@ -34,14 +34,20 @@
 
 #define OS_STACK_SIZE               MBED_CONF_APP_THREAD_STACK_SIZE
 
-#ifndef OS_TIMER_THREAD_STACK_SIZE
-#define OS_TIMER_THREAD_STACK_SIZE  768
+/** The timer thread's stack size can be configured by the application, if not explicitly specified, it'll default to 768 */
+#ifndef MBED_CONF_APP_TIMER_THREAD_STACK_SIZE
+#define MBED_CONF_APP_TIMER_THREAD_STACK_SIZE   768
 #endif
 
-#ifndef OS_IDLE_THREAD_STACK_SIZE
-#define OS_IDLE_THREAD_STACK_SIZE  512
+#define OS_TIMER_THREAD_STACK_SIZE  MBED_CONF_APP_TIMER_THREAD_STACK_SIZE
+
+/** The idle thread's stack size can be configured by the application, if not explicitly specified, it'll default to 512 */
+#ifndef MBED_CONF_APP_IDLE_THREAD_STACK_SIZE
+#define MBED_CONF_APP_IDLE_THREAD_STACK_SIZE    512
 #endif
 
+#define OS_IDLE_THREAD_STACK_SIZE   MBED_CONF_APP_IDLE_THREAD_STACK_SIZE
+
 #define OS_DYNAMIC_MEM_SIZE         0
 
 #if defined(OS_TICK_FREQ) && (OS_TICK_FREQ != 1000)