Implement a minor space optimization for the PCH identifier table,
which eliminates the storage for IdentifierInfo in the "uninteresting
identifier" cases. Sadly, this only brought back 7k of the 500k we
lost :(


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@70325 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed