These are identified by misc-include-cleaner. I've filtered out those
that break builds. Also, I'm staying away from llvm-config.h,
config.h, and Compiler.h, which likely cause platform- or
compiler-specific build failures.
IssueHash is an attempt to introduce stable warning identifiers
that won't change when code around them gets moved around.
Path diagnostic consumers print issue hashes for the emitted diagnostics.
This move will allow us to ultimately move path diagnostic consumers
to libAnalysis.
Differential Revision: https://reviews.llvm.org/D67421
