[clang-tools-extra] [include-cleaner] Respect language when tracking IWYU pragmas on stdlib headers (PR #152142)

[kadir çetinkaya via cfe-commits]

kadircet wrote:

merging without review, as the change is rather trivial. if you have concerns feel free to leave comments, I am happy to revert or address them post-merge.

https://github.com/llvm/llvm-project/pull/152142