check-clang-tools: Prune 'clang' stuff. Clang is not used here.

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@196804 91177308-0d34-0410-b5e6-96231b3b80d8
[CMake] clang-tools-extra may not depend on LLVM CodeGen.

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@196805 91177308-0d34-0410-b5e6-96231b3b80d8