Include missing header to fix the build after Clang r327573
Include missing header to fix the build after Clang r327573

The "clang/Tooling/CompilationDatabase.h" header is no longer included
by "clang/Tooling/Tooling.h".

apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang