Figure out how to test the cygwin + mingw Windows versions

[mithro]

I copied the following lines;

  # On Cygwin / MINGW use Linux?
  ifneq (, $(findstring Cygwin, $(UNAME_S)))
    OS_FLAG := Linux
  endif
  ifneq (, $(findstring MINGW, $(UNAME_S)))
    OS_FLAG := Linux
  endif

from the changes that @daniellimws did to the python-symbiflow-v2x repository.

If we want to continue to support these configurations, we should figure out how to test them on Travis.

[mithro]

There is some potential information at https://docs.travis-ci.com/user/reference/windows/#how-do-i-use-msys2

Travis CI Documentation

The Windows Build Environment

[mithro]

@daniellimws -- Do you have any idea / thoughts on how to do this?

[daniellimws]

@mithro Sorry but I am using MacOS so don't really think I can help.

[mithro]

@xobs - This is one of the issues I could use Window users help with...

[mithro]

@umarcor -- Think this can be done with github actions now?