[compiler-rt] [Fuzzer] Enable custom libc++ for Android (PR #70407)

[Ryan Prichard via llvm-commits]

rprichard wrote:

I uploaded https://github.com/llvm/llvm-zorg/pull/66 to remove the redundant options. I tried to run `buildbot_android.sh`, and it was able to build things, but failed because it couldn't connect to an arm32 device. The https://github.com/llvm/llvm-project/pull/70534 PR is also needed if the buildbot tests libFuzzer, but I think it isn't necessary to set `ANDROID_NATIVE_API_LEVEL` because the sanitizer buildbots are already targeting API 24, which supports `_FILE_OFFSET_BITS=64` on 32-bit targets. (I think I'll merge the #70534 PR tomorrow.)

https://github.com/llvm/llvm-project/pull/70407