Add documentation for source based distributions like Gentoo

[Eiji7]

I have found solution for my second problem and described how to solve it in forum post for Gentoo and Gentoo-based Linux distributions. It would be nice if someone using beautiful sentences could describe it to not cause such troubles for others.

[boydm]

I've been following the thread on the forums. Lets confirm here what the steps are. Can you summarize them?

[Eiji7]

@boydm Sure, no problem

In Gentoo we do not have *-dev packages like in Ubuntu. Of course we have a bit different package names, so we have such requiements:

media-libs/glew
media-libs/glfw
virtual/pkgconfig

Just have read *.ebuild file. If I understand it correctly we need to disable wayland support for this package in order to run it under X window system (otherwise it does not require X11 libraries), so for Gentoo and Gentoo-based distributions we need to add entry to /etc/portage/package.use:

media-libs/glfw -wayland

Also I have found this:

GLFW natively supports Windows, macOS and Linux and other Unix-like systems. Experimental implementations for the Wayland protocol and the Mir display server are available but not yet officially supported.
Source: https://github.com/glfw/glfw/blob/master/README.md

In short for now we should not try scenic on Wayland at least until it would have official and stable support in media-libs/glfw.