Merge pull request swiftlang#39773 from mikeash/fix-allocationmetadatapointer

[Reflection] Fix ReflectionContext::allocationMetadataPointer.

Author: mikeash

include/swift/Reflection/ReflectionContext.h

@@ -1153,7 +1153,6 @@ class ReflectionContext
     MetadataAllocation<Runtime> Allocation) {
     if (Allocation.Tag == GenericMetadataCacheTag) {
         struct GenericMetadataCacheEntry {
-          StoredPointer Left, Right;
           StoredPointer LockedStorage;
           uint8_t LockedStorageKind;
           uint8_t TrackingInfo;