For PR11916: Add support for g++'s __int128 keyword. Unlike __int128_t, this is
a type specifier and can be combined with unsigned. This allows libstdc++4.7 to
be used with clang in c++98 mode.

Several other changes are still required for libstdc++4.7 to work with clang in
c++11 mode.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@153999 91177308-0d34-0410-b5e6-96231b3b80d8
14 files changed