setup.py assumes MSVC on Windows

[us88]

trafficstars

We'd like to use MinGW on Windows to compile this library, though line 22 is appending "/O2" explicitly:

cargs = ('/O2' if iswindows else '-O3').split()

There should probably be something in place to detect if someone is using Microsoft's Compiler or Clang or GCC

[kovidgoyal]

You are welcome to send a patch for it, I never use non-native compilers for platforms that have native compilers.