Blender Git Loki

Stop object shaders from being updated when changing lamp properties

Object shaders no longer depend on lamp data at compile time, thus they
don't need to be invalidated when lamps change. Disabling shader
recompilation allows fast viewport updates when changing lamp settings.

Note that even though shaders for lamps are currently not being used,
`lamp_changed` is still freeing the lamp shaders, as at some point we
might want to use shaders for lamps...