Revert "Make static counters in ASTContext non-static."

This reverts commit r354795, I suspect it is causing test failures
on MSan sanitizer bots.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@354812 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed