Merge pull request #36228 from ktoso/wip-groups-towards-clean-abi

[TaskGroup] Towards ABI stability of groups

Author: ktoso

include/swift/ABI/MetadataValues.h

@@ -46,6 +46,9 @@ enum {
   /// The number of words (in addition to the heap-object header)
   /// in a default actor.
   NumWords_DefaultActor = 10,
+
+  /// The number of words in a task group.
+  NumWords_TaskGroup = 32,
 };
 
 struct InProcess;
@@ -121,6 +124,9 @@ const size_t MaximumAlignment = 16;
 /// The alignment of a DefaultActor.
 const size_t Alignment_DefaultActor = MaximumAlignment;
 
+/// The alignment of a TaskGroup.
+const size_t Alignment_TaskGroup = MaximumAlignment;
+
 /// Flags stored in the value-witness table.
 template <typename int_type>
 class TargetValueWitnessFlags {