PCH: When writing PCH files, tweak the predicate function deciding whether to mark a decl as "external" to be closer to reality. 

This still isn't perfect, but I believe it is conservatively accurate at marking decls which IRgen needs to see, while still keeping the "deserialization footprint" on Cocoa.h.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@82112 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed