[Driver] Clean up some Separate form options
Drop the Separate form of -fmodule-name X, -fprofile-remapping-file X, and -frewrite-map-file X.
To the best of my knowledge they are not used. Their conventional Joined forms (-fFOO=) should be used instead.
-fdebug-compilation-dir X is used in several places, e.g. chromium/infra/goma.
It is also advertised in http://blog.llvm.org/2019/11/deterministic-builds-with-clang-and-lld.html
So we keep it but make the EQ form canonical and the Separate form an alias.
Differential Revision: https://reviews.llvm.org/D96886