Fixed erroneous comparison

src/core/malloc.c

 			 * (which can happen only at the very end of
 			 * the heap).
 			 */
-			if ( ( size_t ) post_size > MIN_MEMBLOCK_SIZE ) {
+			if ( ( size_t ) post_size >= MIN_MEMBLOCK_SIZE ) {
 				post->size = post_size;
 				list_add ( &post->list, &pre->list );
 			}