glsl: Add new uniform_field_visitor::visit_field variant

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Carl Worth <cworth@cworth.org>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/glsl/linker.h

@@ -95,6 +95,16 @@ protected:
    virtual void visit_field(const glsl_type *type, const char *name,
                             bool row_major) = 0;
 
+   /**
+    * Visit a record before visiting its fields
+    *
+    * For structures-of-structures or interfaces-of-structures, this visits
+    * the inner structure before visiting its fields.
+    *
+    * The default implementation does nothing.
+    */
+   virtual void visit_field(const glsl_struct_field *field);
+
 private:
    /**
     * \param name_length  Length of the current name \b not including the