modified mesh_system.c to improve memory

Author: Roberto Spelta

features/nanostack/FEATURE_NANOSTACK/mbed-mesh-api/source/mesh_system.c

@@ -31,7 +31,7 @@
 
 /* Heap for NanoStack */
 #if !MBED_CONF_MBED_MESH_API_USE_MALLOC_FOR_HEAP
-static uint8_t app_stack_heap[MBED_CONF_MBED_MESH_API_HEAP_SIZE + 1];
+static uint8_t app_stack_heap[MBED_CONF_MBED_MESH_API_HEAP_SIZE + 1] __attribute__(( section( "mesh_heap") ));
 #else
 static uint8_t *app_stack_heap;
 #endif