Sink a #include while we're here. NFC.

Format.h doesn't use stack.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@220879 91177308-0d34-0410-b5e6-96231b3b80d8
clang-format: Format line if invoked on the trailing newline.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@220883 91177308-0d34-0410-b5e6-96231b3b80d8