mm: Add CONFIG_MM_PANIC_ON_FAILURE option

While allocation failure here is not necessarily abnormal enough to
warrant a panic in general, it can be useful in certain situations.

mm/Kconfig

@@ -201,4 +201,9 @@ config MM_DUMP_ON_FAILURE
 	default n
 	depends on DEBUG_MM
 
+config MM_PANIC_ON_FAILURE
+	bool "Panic on allocation failure"
+	default n
+	depends on DEBUG_MM
+
 source "mm/iob/Kconfig"

mm/mm_heap/mm_malloc.c

@@ -255,6 +255,9 @@ FAR void *mm_malloc(FAR struct mm_heap_s *heap, size_t size)
             minfo.arena, minfo.uordblks, minfo.fordblks,
             minfo.mxordblk, minfo.aordblks, minfo.ordblks);
       mm_memdump(heap, -1);
+#endif
+#ifdef CONFIG_MM_PANIC_ON_FAILURE
+      PANIC();
 #endif
     }
 #endif