Store the full list of pending instantiations in a chained PCH. Previously we...

Store the full list of pending instantiations in a chained PCH. Previously we attempted to store only new pending instantiations, but our filter was incorrect, dropping implicit instantiations of class template members. It's just not worth coming up with a complex filter that is correct, when the only cost is PCH files that are a few hundred bytes (at most) larger.

llvm-svn: 130098