[compiler-rt] [compiler-rt] allow removing libc dependency on Android (PR #152394)

[Axel Karjalainen via llvm-commits]

axelkar wrote:

> > The upside is that we have an initial compiler-rt without a dependency to libc, which is useful for building Bionic libc.
> 
> as the main bionic maintainer for the last 10+ years, this is the bit i don't get --- bionic builds just fine :-)
> 
> (but this is also why i added pirama, because he owns the "building llvm" side of android, and he might be familiar with whatever llvm bootstrapping problem (?) you're talking about...)

Oops.. [Bionic does use `-fno-builtin`](https://android.googlesource.com/platform/bionic/+/4b1e9a07d96b598e7758fe263088163dc5098ff7/libc/Android.bp#48). No worries about that then! I assumed it would require builtins.

Just as a side note: Doesn't `libc_hwasan` require you to have built compiler-rt's sanitizers that require Bionic's libc?

https://github.com/llvm/llvm-project/pull/152394