Fix buildbot: work around missing GCC C++11 feature.


git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@214459 91177308-0d34-0410-b5e6-96231b3b80d8
clang-format vs plugin: claim support for VS 14 CTP too

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@214461 91177308-0d34-0410-b5e6-96231b3b80d8