Unify all heaps (stdlib + LVGL + FreeRTOS) into a single heap managed by FreeRTOS and heap_4_infinitime.c.

LVGL supports custom implementation of malloc() and free() so using pvPortMalloc() and vPortFree() is just a matter of setting the right variables.

Other libraries (NimBLE, LittleFS) and InfiniTime code (new) call malloc() and free() from stdlib. InfiniTime now provides the file stdlib.c that provides a custom implementation for malloc(), free(), calloc() and realloc(). This ensures that all calls to the standard allocator are redirected to the FreeRTOS memory manager.

Note that realloc() is needed by NimBLE.

src/libs/lv_conf.h

@@ -71,7 +71,7 @@ typedef int16_t lv_coord_t;
  * The graphical objects and other related data are stored here. */
 
 /* 1: use custom malloc/free, 0: use the built-in `lv_mem_alloc` and `lv_mem_free` */
-#define LV_MEM_CUSTOM      0
+#define LV_MEM_CUSTOM      1
 #if LV_MEM_CUSTOM == 0
 /* Size of the memory used by `lv_mem_alloc` in bytes (>= 2kB)*/
 #define LV_MEM_SIZE    (14U * 1024U)
@@ -86,9 +86,9 @@ typedef int16_t lv_coord_t;
 /* Automatically defrag. on free. Defrag. means joining the adjacent free cells. */
 #define LV_MEM_AUTO_DEFRAG  1
 #else       /*LV_MEM_CUSTOM*/
-#define LV_MEM_CUSTOM_INCLUDE <stdlib.h>   /*Header for the dynamic memory function*/
-#define LV_MEM_CUSTOM_ALLOC   malloc       /*Wrapper to malloc*/
-#define LV_MEM_CUSTOM_FREE    free         /*Wrapper to free*/
+#define LV_MEM_CUSTOM_INCLUDE <FreeRTOS.h>   /*Header for the dynamic memory function*/
+#define LV_MEM_CUSTOM_ALLOC   pvPortMalloc       /*Wrapper to malloc*/
+#define LV_MEM_CUSTOM_FREE    vPortFree         /*Wrapper to free*/
 #endif     /*LV_MEM_CUSTOM*/
 
 /* Use the standard memcpy and memset instead of LVGL's own functions.