title: Make with multiple compilers
body: <p>When using C++14/C++11 features and STL includes, GCC and clang have different behaviors.  Libc++ has a tendency to include things implicitly, while libstdc++ seems to have a tendency to require explicit includes.  GCC -Wpedantic seems to be a little more pedantic than clang -Wpedantic.</p>
  
  <p>What I want is to have a makefile that attempts to build with both of these compilers, in order to catch errors.  What is the best way to do this?</p>