eglinfo: add command line options

I tried to make it share code with other glinfo tools, but a lot of glinfo_common is about "if _WIN32 is defined, this is wglinfo; if not, this is glxinfo" which puts eglinfo in an awkward position. So, I had to give up on that.

Usage: eglinfo [-h] [-B] [-a <api>] [-p <platform>]
         -h      This message.
         -B      Brief output, print only the basics.
         -a      Print information for a specific API, if supported.
                 (gl, glcore, gles)
         -p      Print information for a specific platform, if supported.
                 (android, gbm, wayland, x11, surfaceless)

This is based on !100 (merged). Also includes a bugfix with pre-1.4 EGL (but I hope no one is still using it now).

Closes: #18 (closed)