Revert "cpp11-migrate: Fixing autoconf build after adding libclangReplace dependency"

Revert "cpp11-migrate: Refactor for driver model of operation"

This reverts commit r189691.
This reverts commit r189689.

This was breaking the phase 1 OS X build for ~2 hours.

https://smooshbase.apple.com/buildbot-internal/builders/phase1%20-%20sanity/builds/9559

I reverted the latter commit since I think the latter depended on the former.

llvm-svn: 189700