fix: cast linker value for configTOTAL_HEAP_SIZE

Fixes #42

Author: fpistm

src/FreeRTOSConfig_Default.h

@@ -99,7 +99,7 @@ extern char _Min_Stack_Size; /* Defined in the linker script */
 #define configMINIMAL_STACK_SIZE          ((uint16_t)((uint32_t)&_Min_Stack_Size/8))
 #endif
 #ifndef configTOTAL_HEAP_SIZE
-#define configTOTAL_HEAP_SIZE             ((size_t)(&_estack - _Min_Stack_Size - &_end))
+#define configTOTAL_HEAP_SIZE             ((size_t)((uint32_t)&_estack - (uint32_t)&_Min_Stack_Size - (uint32_t)&_end))
 #endif
 #ifndef configISR_STACK_SIZE_WORDS
 #define configISR_STACK_SIZE_WORDS        ((uint32_t)&_Min_Stack_Size/4)