Ability to use libstdc++11 with clang

[conan-io]

Ability to use libstdc++11 with clang

[memsharded]

I am not sure, because conan_cmake_detect_gnu_libcxx checks for gcc flag _GLIBCXX_USE_CXX11_ABI which doesn't make much sense in clang. It also checks version against "5.1" to try to define libstdc++11 as the one being used.

So it might be necessary to add custom clang logic for this. I am fine with keeping _GLIBCXX_USE_CXX11_ABI as the flag to check if clangs ignores it.

[r4zzz4k]

Sorry, I managed to miss your answer and forgot about the issue for a bit.
From what I see in libstdc++ documentation, all _GLIBCXX_ macros, including _GLIBCXX_USE_CXX11_ABI, are related to libstdc++, not to gcc toolchain. As clang also uses libstdc++, I believe it's okay to use mentioned macro to detect library version.

[memsharded]

Ok, got it, fixed it in #50, please have a look and report if necessary. Thanks!

[r4zzz4k]

Cool! I'll try to pull new config and rebuild the project tomorrow, but I've made same changes locally (sorry for not providing proper PR).
Thanks once again for your great efforts!

[memsharded]

Thanks to you for the feedback, don't worry!
It is on master branch, I haven't created a proper release/tag for it, but if everything looks good, I'll create a new one.