Fix heap configuration error with armcc

In rtos/rtx/TARGET_CORTEX_M/RTX_CM_lib.h, Image$$ARM_LIB_HEAP$$Base/Image$$ARM_LIB_HEAP$$Length will cause zero memory allocation.
Fix it with Image$$ARM_LIB_HEAP$$ZI$$Base/Image$$ARM_LIB_HEAP$$ZI$$Length. This is to place heap at external SRAM.

Author: ccli8

rtos/rtx/TARGET_CORTEX_M/RTX_CM_lib.h

@@ -579,12 +579,12 @@ osThreadDef_t os_thread_def_main = {(os_pthread)pre_main, osPriorityNormal, 1U,
 
 #elif defined(TARGET_NUMAKER_PFM_NUC472)
 #   if defined(__CC_ARM)
-extern uint32_t                 Image$$ARM_LIB_HEAP$$Base[];
-extern uint32_t                 Image$$ARM_LIB_HEAP$$Length[];
+extern uint32_t                 Image$$ARM_LIB_HEAP$$ZI$$Base[];
+extern uint32_t                 Image$$ARM_LIB_HEAP$$ZI$$Length[];
 extern uint32_t                 Image$$ARM_LIB_STACK$$ZI$$Base[];
 extern uint32_t                 Image$$ARM_LIB_STACK$$ZI$$Length[];
-#define HEAP_START              ((unsigned char*) Image$$ARM_LIB_HEAP$$Base)
-#define HEAP_SIZE               ((uint32_t) Image$$ARM_LIB_HEAP$$Length)
+#define HEAP_START              ((unsigned char*) Image$$ARM_LIB_HEAP$$ZI$$Base)
+#define HEAP_SIZE               ((uint32_t) Image$$ARM_LIB_HEAP$$ZI$$Length)
 #define ISR_STACK_START         ((unsigned char*)Image$$ARM_LIB_STACK$$ZI$$Base)
 #define ISR_STACK_SIZE          ((uint32_t)Image$$ARM_LIB_STACK$$ZI$$Length)
 #   elif defined(__GNUC__)