[llvm] [NFC][DebugInfo] Make MDNodeKeyImpl<DILocation>::Column 16 bits (PR #143399)

[Nikita Popov via llvm-commits]

https://github.com/nikic approved this pull request.

LGTM, though I wonder whether we should also change the ctor to accept uint16_t?

https://github.com/llvm/llvm-project/pull/143399