clang trunk non-deterministic on both x86_64 linux and darwin

FYI. I finally got a chance to test the three test cases that I found
for the non-deterministic code generation from clang trunk on x86_64
linux. The March 30th nightly build for ubuntu zesty x86_64 produces
the same differing assembly as seen on x86_64 darwin..
ps The three reproducers are available on as ELFDumper.ii,
ClangTidyDiagnosticConsumer.ii and SourceCoverageViewHTML.ii.