Remove unused includes of clang/Config/config.h

Remove unused includes of clang/Config/config.h

Found by opening config.h.cmake in vim, finding all defined macros with

  /define\(01\)\? \zs[A-Za-z0-9_]*<cr>
  :%s//\=setreg('A', submatch(0), 'V')/gn<cr>
  :put A<cr>

and then joining them all with |, and passing that to

  git grep -E that_pattern 'clang/*.h' 'clang/*.cpp' 'clang/*.c'

and diffing that output with the result of

  git grep Config/config.h 'clang/*.h' 'clang/*.cpp' 'clang/*.c'

No intended behavior change.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@331124 91177308-0d34-0410-b5e6-96231b3b80d8