intel/compiler: Introduce backend_shader method to propagate IR changes to analysis passes

The invalidate_analysis() method knows what analysis passes there are
in the back-end and calls their invalidate() method to report changes
in the IR.  For the moment it just calls invalidate_live_intervals()
(which will eventually be fully replaced by this function) if anything
changed.

This makes all optimization passes invalidate DEPENDENCY_EVERYTHING,
which is clearly far from ideal -- The dependency classes passed to
invalidate_analysis() will be refined in a future commit.

Reviewed-by: Matt Turner <mattst88@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4012>

src/intel/compiler/brw_vec4_copy_propagation.cpp

@@ -559,7 +559,7 @@ vec4_visitor::opt_copy_propagation(bool do_constant_prop)
    }
 
    if (progress)
-      invalidate_live_intervals();
+      invalidate_analysis(DEPENDENCY_EVERYTHING);
 
    return progress;
 }