This mesh will later be used to render only damaged portions of the desktop.
We also moved the coordinate transformation for damage overlay into a matrix
and computed by the shader.
The way things were handled in EGLTexture is not only very hard to
follow, but broken. This change set breaks up EGLTexture into a modular
design making it easier to implement the various versions.
Note that DMABUF is currently broken and needs to be re-implemented.
The $escape+S keybinding now cycles through the available scale algorithms.
This allows the user to switch between algorithms if the automatic detection
turns out to be problematic.
The algorithms are renumbered so that 0 can be LG_SCALE_AUTO.
Instead of duplicating the #defines from the shader into the C code,
this commit adds a custom CMake rule that exports all the #defines
from a shader into a C header.
