First step towards adding a parent map to the ASTContext.

This does not yet implement the LimitNode approach discussed.

The impact of this is an O(n) in the number of nodes in the AST
reduction of complexity for certain kinds of matchers (as otherwise the
parent map gets recreated for every new MatchFinder).

See FIXMEs in the comments for the direction of future work.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176251 91177308-0d34-0410-b5e6-96231b3b80d8
No spaces around pointers to members.

Before: (a ->* f)()
After:  (a->*f)()

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176252 91177308-0d34-0410-b5e6-96231b3b80d8
Improve property metadata generation with the GNUstep runtime.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176254 91177308-0d34-0410-b5e6-96231b3b80d8