[compiler-rt] [ASan] Update meminstrinsics to use library memmove rather than internal (PR #160740)

[Marco Elver via llvm-commits]

melver wrote:

> > LGTM - do we need tests for this so it doesn't regress?
> 
> I can't see any tests for the memintrinsics stuff; do you think there's anything that we could be testing here @melver?

I thought we should at least have tests they behave as expected when instrumented. But if they don't exist yet, perhaps nothing to do.
Did you encounter a particular issue that could be reproduced and used as a test?
In any case, feel free to submit.

https://github.com/llvm/llvm-project/pull/160740