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

[Dan Blackwell via llvm-commits]

DanBlackwell wrote:

Oh, looks like `memmove` is tested here: https://github.com/llvm/llvm-project/blob/f6fc5e83d71e643518c63acb5e43847cd1813895/compiler-rt/test/asan/TestCases/memset_test.cpp#L57

@melver what's your opinion on changing this test name to `memintrinsics_test.cpp`? It seems to cover the three mem* functions implemented in [asan_interceptors_memintrinsics.cpp‎](https://github.com/llvm/llvm-project/pull/160740#diff-26b81e5569d03cafc72c5b1d5dab2a7fa65df7e22849be2b4300fec3e8182e62), rather than just memset as the name currently suggests.

> Did you encounter a particular issue that could be reproduced and used as a test?

I came across this while looking at some profiling data (I was surprised to see a bunch of samples with `internal_memmove` being called from outside of the Asan library).

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