cpp11-migrate: Add -for-compilers command line switch.

This change add a new option command line option -for-compilers that allows the
user to enable multiple transforms automatically.

Another difference is that now all transforms are enabled by default.

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@187360 91177308-0d34-0410-b5e6-96231b3b80d8