Implement the first piece of a -Wc++98-compat flag so that people can build in
C++11 mode but keep their sources compatible with C++98.  This patch implements
the -Wc++98-compat-variadic-templates sub-flag and -Wc++98-compat to include
it.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@141898 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed