Refactor the way PCHReader tracks whether we are in recursive loading.

-Replace CurrentlyLoadingTypeOrDecl with a counting scheme (NumCurrentElementsDeserializing)
-Provide outside access to the mechanism by adding methods StartedDeserializing/FinishedDeserializing
  to ExternalASTSource.

These are preparation for the next commit.

llvm-svn: 109856
4 files changed
tree: 29d985000043b97e1c05c92b389656fe1b709f02
  1. clang/
  2. compiler-rt/
  3. libcxx/
  4. lldb/
  5. llvm/