[clangd] Handle windows line endings in QueryDriver

Summary:
The previous patch did not fix the end mark. D64789
fixes second case of https://github.com/clangd/clangd/issues/93

Patch by @lh123 !

Reviewers: sammccall, kadircet

Reviewed By: kadircet

Subscribers: MaskRay, ilya-biryukov, jkorous, arphaman, cfe-commits

Tags: #clang-tools-extra, #clang

Differential Revision: https://reviews.llvm.org/D64970

llvm-svn: 366545