GRIM: Disallow changing of hardware acceleration modes if Opengl is not enabled
(cherry picked from commit d76f2ea04de7176a7eda0f8b95aebff7de54a34f)
GRIM: Fix switching fullscreen crashing with tinygl
(cherry picked from commit 570164a2cdc9841d2c754b22fe7d23993340ebed)

Conflicts:
	engines/grim/gfx_tinygl.cpp
GRIM: Reduce code duplication.
(cherry picked from commit 70becefaed8576dbf17217ce98948cb5389cce19)