For the functions from GL_FOO_robustness we want to resolve it by
ourselves in order to add a custom implementation if it's not available.
Unfortunately once epoxy.h is included this breaks as epoxy defines the
names and so through the preprocessor epoxy always wins.
So we need different names: all functions from robustness get a "kwin"
prefix and the usage is changed everywhere in kwin source code.
REVIEW: 125883
As we don't have GLPLatform before the backend is fully created
the AbstractEglBackend has a new method isOpenGLES() -> bool
which determines based on QOpenGLContext::openGLModuleType().
The backend is based on drm's gbm backend and also uses the GBM
platform, but with the default display allowing the driver to pick
a device. In addition it doesn't use a surface, but a surfaceless
context with a framebuffer object to render to. Given that it diverged
too much from drm's backend to allow more code sharing.
If KWin is started from a tty it gets a proper driver, if KWin is started
in a X11 session it only gets llvmpipe. Given that there is a chance that
the autotests using the virtual backend will fail. In that case a follow
up patch will enforce either O2 or Q.
