Merge pull request swiftlang#25019 from jckarter/dont-export-equalContexts

Runtime: Don't export equalContexts.

Author: jckarter

include/swift/Runtime/Metadata.h

@@ -271,7 +271,6 @@ const
 
 /// True if two context descriptors in the currently running program describe
 /// the same context.
-SWIFT_RUNTIME_EXPORT
 bool equalContexts(const ContextDescriptor *a, const ContextDescriptor *b);
 
 /// Compute the bounds of class metadata with a resilient superclass.