[Runtime] Auth args to compareTypeContextDescriptors.

When swift_compareTypeContextDescriptors was added, it did not auth the
TypeContextDesriptor arguments that were passed to it.  Fix that here.

There are not any uses of this function yet, so there are no signs that
need to be added.

Author: nate-chandler

stdlib/public/runtime/Metadata.cpp

@@ -2063,6 +2063,11 @@ bool swift::equalContexts(const ContextDescriptor *a,
 SWIFT_CC(swift)
 bool swift::swift_compareTypeContextDescriptors(
     const TypeContextDescriptor *a, const TypeContextDescriptor *b) {
+  a = swift_auth_data_non_address(
+      a, SpecialPointerAuthDiscriminators::TypeDescriptor);
+  b = swift_auth_data_non_address(
+      b, SpecialPointerAuthDiscriminators::TypeDescriptor);
+
   // The implementation is the same as the implementation of
   // swift::equalContexts except that the handling of non-type
   // context descriptors and casts to TypeContextDescriptor are removed.