Fix the build on 32 bit hosts.

- Add memcpy and memcmp to the stub headers.
- __uint128_t is not available on 32 bit platforms. It's also unused so just
  comment it out for now.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@153779 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed