MS ABI: Update alias template mangling for VC "14" CTP 3

MSVC "14" CTP 3 has fixed it's mangling for alias templates when used as
template-template arguments; update clang to be compatible with this
mangling.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@215972 91177308-0d34-0410-b5e6-96231b3b80d8