Pick correct compiler for CMAKE_CXX_COMPILER

[ozanarmagan]

Fix to solve the problem of picking gcc instead of g++ and clang instead of clang++ by a simple function.

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[ozanarmagan]

Hi @jsharpe, this little trick can fix #931

[jheaff1]

Would this also work when cross compiling, eg with a compiler named “arm-none-eabi-gcc”?

[jheaff1]

Does this mean that pure C libraries (eg openssl and libcurl) will be built with g++ rather than gcc and therefore will unnecessarily link to libstdc++? If so, this change should be optional via a rule attribute