Restore blender@2.79b, the last version that does not require OpenGL 3,
and therefore the last version to work on many older computers. Note
that this commit relies on blender-2.79-newer-ffmpeg.patch and
blender-2.79-python-3.7-fix.patch, which were left in the tree when
blender@2.79b was previously removed in commit
1f14453eed.
* gnu/packages/patches/blender-2.79-gcc8.patch,
gnu/packages/patches/blender-2.79-gcc9.patch,
gnu/packages/patches/blender-2.79-oiio2.patch,
gnu/packages/patches/blender-2.79-python-3.8-fix.patch: New files.
* gnu/local.mk (dist_patch_DATA): Add them.
* gnu/packages/graphics.scm (blender-2.79): New variable.
