XCB/OpenGL resizing incorrectly renders window contents with an offset

[Ruben Van Boxem]

Upstream Mesa bugs:

• https://bugs.freedesktop.org/show_bug.cgi?id=42131
• https://bugs.freedesktop.org/show_bug.cgi?id=35945

Possible workarounds:

• LIBGL_ALWAYS_INDIRECT=1
• use CPU rendering

It seems Mesa is missing some important X events and the GL context viewport may not be properly updated

[Ruben Van Boxem]

This should be fixed by commit da03a90