Fix micro performance issue

m-array.h

@@ -289,6 +289,7 @@
     type *ret = &v->ptr[v->size];                                       \
     v->size++;                                                          \
     ARRAYI_CONTRACT(v);                                                 \
+    M_ASSUME(ret != NULL);						\
     return ret;                                                         \
   }                                                                     \
                                                                         \