[clang] [clang][DebugInfo] Cache repeated debug info lookups (PR #193785)

[Cullen Rhodes via cfe-commits]

c-rhodes wrote:

it looks like we've been working in the same area. I've also been working on compile-time and noticed this whilst profiling sqlite. I posted #193918 shortly after you posted this, sorry I've only just noticed your PR, this isn't an area i usually work in.

It looks like what's common between our patches is caching line/column, but I'm seeing a bigger geomean improvement by also caching file.

https://github.com/llvm/llvm-project/pull/193785