Remove runtime dependencies on libstdc++

[MichalStrehovsky]

Transferred from dotnet/corert#3564.

NativeAOT runtime does not use any C++ features (exception handling, etc.), but it still depends on libstdc++ here and there for no good reason. Consider cleaning these up and remove dependency on libstdc++ to improve minimal footprint.

[am11]

This removes the dependency from linux (clang, gcc) and osx (clang) main...am11:runtime:feature/nativeaot/nostdlib++.

I haven't tested on windows, but I am sure its support needs work.

[MichalStrehovsky]

Neat! Thank you for looking into it! Could you please submit it as a pull request?

We probably don't need to worry about Windows - Windows doesn't distinguish between C and C++ runtime support - it's all in a single library that is present on all OSes. It's most interesting on Linux because the most minimal distros only come with a libc and C++ is an extra dependency one needs to install (as demonstrated here: https://github.com/eerhardt/Albums/blob/104ae182f72dccf522092ec33a340b8eb02529b7/AlbumsNetCore/Dockerfile#L2).

[driver1998]

We probably don't need to worry about Windows - Windows doesn't distinguish between C and C++ runtime support

Is it possible to only depend on UCRT on Windows?

[josephmoresena]

Would this remove the libc++_shared.so library dependency on Android?

[jkotas]

Is it possible to only depend on UCRT on Windows?

We are statically linking the tiny bit of C++ runtime that we need on Windows already. We do not depend on any C++ runtime .dll on Windows.

[josephmoresena]

@josephmoresena, this issue is for coreclr NativeAOT. Android NativeAOT is related to mono runtime (different sources and configurations). @lambdageek, do you know if libc++_shared.so dependency removal is feasible? I do not have a developer environment for Android, so it is hard to assess from reading the code. 😁

I actually talk about coreclr. @MichalStrehovsky made a branch to allow build it using the NDK.

Currently for some reason the upgrade of that branch is broken but it was usefull in order to create JNI libraries with pure C#.