Implemented #pragma GCC warning/error in the same mould as #pragma message.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179687 91177308-0d34-0410-b5e6-96231b3b80d8
DR974: Lambdas can have default arguments.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179688 91177308-0d34-0410-b5e6-96231b3b80d8