Auto merge of #182 - ecoal95:egl, r=larsbergstrom
Auto merge of #182 - ecoal95:egl, r=larsbergstrom

Add libgles2-mesa-dev to the list of servo dependencies

This will allow linux running over EGL instead of GLX (see
https://github.com/servo/servo/issues/7484), and is currently blocking
https://github.com/servo/servo/pull/9044, even though it can be worked
out.

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servo/saltfs,setupminimal/saltfs,UK992/saltfs,UK992/saltfs,ALikhachev/saltfs,setupminimal/saltfs,UK992/saltfs,rwaweber/saltfs,ALikhachev/saltfs,ALikhachev/saltfs,setupminimal/saltfs,rwaweber/saltfs,rwaweber/saltfs,servo/saltfs