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_fs.h

@@ -126,6 +126,7 @@ public:
                       unsigned *out_pull_index);
    void lower_constant_loads();
    void invalidate_live_intervals();
+   virtual void invalidate_analysis(brw::analysis_dependency_class c);
    void calculate_live_intervals();
    void calculate_register_pressure();
    void validate();