Draft: eglinfo: Add renderer and command line options

This merge request was initially aimed at adding the renderer to eglinfo.

However, to get to the renderer, it needs to create a context.

Unfortunately eglinfo links to libGL which may or may not be able to create a GLES context (apparently, it works with Mesa, not sure about others) so using something like epoxy which takes care of dlopen'ing the right libs would be interesting.

With adding even more info to eglinfo, it might be desirable to give users the ability to specify the platform or API they want to query.

So this series of patches does:

• Add an optional dependency on epoxy
• Reports the renderer for all API
• Add command line options support to limit the platform and API if desired.

e.g.:

$ elginfo [-h] [-c] [-a <api>] [-p <platform>]
	 -h: This message
	 -a <api>: Prints renderer for an API if supported.
	    ("glcore", "gles", "vg")
	 -p <platform>: Prints information for a platform if supported.
	    ("android", "gbm", "wayland", "x11", "surfaceless", "device", "none")