Concurrency: Suppress -Wnontrivial-memcall warning in Actor.cpp.

NFC.

Author: tshortli

stdlib/public/Concurrency/Actor.cpp

@@ -2774,7 +2774,8 @@ swift::swift_distributedActor_remote_initialize(const Metadata *actorType) {
 
   // TODO: remove this memset eventually, today we only do this to not have
   //       to modify the destructor logic, as releasing zeroes is no-op
-  memset(alloc + 1, 0, metadata->getInstanceSize() - sizeof(HeapObject));
+  memset((void *)(alloc + 1), 0,
+         metadata->getInstanceSize() - sizeof(HeapObject));
 
   // TODO(distributed): a remote one does not have to have the "real"
   //  default actor body, e.g. we don't need an executor at all; so