Allow force updating the NumCreatedFIDsForFileID.
Allow force updating the NumCreatedFIDsForFileID.

Our internal clients implement parsing cache based on FileID. In order for the
Preprocessor to reenter the cached FileID it needs to reset its
NumCreatedFIDsForFileID.

Differential Revision: https://reviews.llvm.org/D51295


git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@347304 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang