Change Sema's UnusedStaticFuncs to UnusedFileScopedDecls to allow also keeping track of unused file scoped variables.

    This is only preparation, currently only static function definitions are tracked, as before.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@111025 91177308-0d34-0410-b5e6-96231b3b80d8
7 files changed