Arguments parsing on Windows

[smokku]

Emu uses argp for argument parsing and --help.

> ./emu --help

Usage: emu [OPTION...] [ROM.xex]
X65 microcomputer emulator

  -l, --labels=LABELS_FILE   Load VICE compatible global labels file
  -o, --output=FILE          Output to FILE instead of standard output
  -q, -s, --quiet, --silent  Don't produce any output
  -v, --verbose              Produce verbose output
  -?, --help                 Give this help list
      --usage                Give a short usage message
  -V, --version              Print program version

Mandatory or optional arguments to long options are also mandatory or optional
for any corresponding short options.

Report bugs to: https://github.com/X65/emu/issues

Due to lack of support on Windows, it is disabled in Windows build, leaving the user without obvious way of loading files.

We need to find a replacement for windows build or a way of bundling argp with Windows build.