Add parsing support for C++ classes.

Note that Parser::ParseCXXMemberSpecification is temporarily disabled until the Sema support is in place.
Once ParseCXXMemberSpecification is enabled, the Parser/cxx-class.cpp test will pass.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@52694 91177308-0d34-0410-b5e6-96231b3b80d8
11 files changed