Rebuild the nested name specifiers in member-pointer declarator chunks when

entering the current instantiation.  Set up a little to preserve type location
information for typename types while we're in there.

Fixes a Boost failure.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@102673 91177308-0d34-0410-b5e6-96231b3b80d8