[llvm-branch-commits] [clang] [Clang][Lex] Fix __has_include_next to return false when no valid next dir (PR #173717)

[Zachary Fogg via llvm-branch-commits]

zfogg wrote:

cc @jansvoboda11 @AaronBallman - This is a backport of a fix for `__has_include_next` behavior when a file is found via absolute path. Would appreciate a review when you have time.

https://github.com/llvm/llvm-project/pull/173717