[NFC][clang] Mark P3034R1 as implemented (#177150)
Mark [P1857R3 Modules Dependency Discovery](https://wg21.link/p1857r3)
as implemented.
This paper was implemented in
https://github.com/llvm/llvm-project/pull/173789.
Signed-off-by: yronglin <yronglin777@gmail.com>
