[index] Update in IndexingAction.cpp for upstream change
[index] Update in IndexingAction.cpp for upstream change

rdar://39287442

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