fix new introduced issue: RT_ASSERT(mem->magic != HEAP_MAGIC);

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@1341 bbd45198-f89e-11dd-88c7-29a3b14d5316

src/mem.c

@@ -498,7 +498,7 @@ void rt_free(void *rmem)
 
 	/* ... which has to be in a used state ... */
 	RT_ASSERT(mem->used);
-	RT_ASSERT(mem->magic != HEAP_MAGIC);
+	RT_ASSERT(mem->magic == HEAP_MAGIC);
 	/* ... and is now unused. */
 	mem->used = 0;
 	mem->magic = 0;