Runtime: silence some warnings

Silence warnings about deleted defaulted constructors due to the
non-trivial constructor for the atomic type.  Guard a conditionally used
function with the appropriate guard.

Author: compnerd

stdlib/public/runtime/SwiftObject.mm

@@ -583,13 +583,14 @@ static bool isNonNative_unTagged_bridgeObject(void *object) {
   return (uintptr_t(object) & objectPointerIsObjCBit) != 0
       && (uintptr_t(object) & heap_object_abi::BridgeObjectTagBitsMask) == 0;
 }
-#endif
 
 /// Return true iff the given BridgeObject is a tagged value.
 static bool isBridgeObjectTaggedPointer(void *object) {
-	return (uintptr_t(object) & heap_object_abi::BridgeObjectTagBitsMask) != 0;
+  return (uintptr_t(object) & heap_object_abi::BridgeObjectTagBitsMask) != 0;
 }
 
+#endif
+
 // Mask out the spare bits in a bridgeObject, returning the object it
 // encodes.
 ///

stdlib/public/runtime/WeakReference.h

@@ -189,7 +189,7 @@ class WeakReference {
 
  public:
 
-  WeakReference() = default;
+  WeakReference() : nativeValue() {}
 
   WeakReference(std::nullptr_t)
     : nativeValue(WeakReferenceBits(nullptr)) { }