Wayland implementation to ogles2_helper_wayland.c

Move Wayland-specific code of ogles2_helper into its
own module, so we can support different EGL platforms.
Window system abstraction: Test OpenGL ES on fbdev

Abstract window system-specific functions and add command-line
option (-ws) for choosing between wayland and fbdev.

Run smoke tests for both wayland and fbdev. Performance tests
are only run on wayland at the moment, but can be made to run
on fbdev by duplicating the test sets in tests.xml.

[ogles2_helper] Add support for testing OpenGL ES 2.0 on fbdev
Merge pull request #4 from thp/fbdev

Add support for testing on fbdev