[libc] [llvm] [libc] clean up string_utils memory functions (PR #143031)

[via llvm-commits]

Kewen12 wrote:

Hi @michaelrj-google, it seems the fix build successfully but failed a check. Appreciated if you could take another look.
>/home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.src/libc/test/integration/startup/gpu/rpc_stream_test.cpp:84:3: error: use of undeclared identifier 'inline_memset'
   84 |   inline_memset(buffer, 0, offset);
      |   ^~~~~~~~~~~~~
1 error generated.

buildbot: https://lab.llvm.org/buildbot/#/builders/10/builds/6850

https://github.com/llvm/llvm-project/pull/143031