Introduce '-chain-include' option to specify headers that will be converted to chained PCHs in memory
without having to use multiple runs and intermediate files.

Intended for testing & debugging of chained PCH.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@127339 91177308-0d34-0410-b5e6-96231b3b80d8
11 files changed