Update init.c

Fix
diff --git a/src/init.c b/src/init.c
index 79ab6ee..e5c1142 100644
--- a/src/init.c
+++ b/src/init.c
@@ -3432,7 +3432,7 @@
     allocator = &xnn_default_allocator;
   }
   #ifdef _MSC_VER
-    _InterlockedCompareExchangePointer((void* volatile)(&init_allocator), allocator, NULL);
+    _InterlockedCompareExchangePointer((void* volatile*) &init_allocator, allocator, NULL);
   #else
     __sync_bool_compare_and_swap(&init_allocator, NULL, allocator);
   #endif