dri: don't touch the shader compiler

dri: don't touch the shader compiler

This function is for deleting per-screen resources, and the shader
compiler resources are not of such nature. Besides, dri shouldn't
need to even know about the presence of a shader compiler.

These resources will already be released when mesa gets unloaded,
and that should be sufficient.

Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Brian Paul <brianp@vmware.com>