[compiler-rt] [llvm] [nsan] Emit calls to optimized functions (PR #98900)

[Dmitriy Chestnykh via llvm-commits]

chestnykh wrote:

> To me looks good. P.S. Do you mind if we hold off on landing this for a couple of days - I wanted to publish a PR with integration tests, this would give us a bit more confidence that things still work. In the meantime, would be great to try to build a ~relatively large program with this PR, although you might encounter other issues (most likely #98143)

I used eigen math library and samples from [here](https://yang.amp.i.kyoto-u.ac.jp/~yyama/computer/FAQ/eigen/eigensystem.html) .

In assembler output i see calls to some new functions like __nsan_set_value_unknown_16, __nsan_copy_* (they differ at different optimizations levels). And the programs work correctly

https://github.com/llvm/llvm-project/pull/98900