linker: Add a last_field parameter to various program_resource_visitor methods

I also considered renaming visit_field(const glsl_struct_field *) to
entry_record and adding an exit_record method.  This would be more
similar to the hierarchical visitor.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>

src/glsl/link_uniform_blocks.cpp

@@ -68,7 +68,8 @@ private:
    }
 
    virtual void visit_field(const glsl_type *type, const char *name,
-                            bool row_major, const glsl_type *record_type)
+                            bool row_major, const glsl_type *record_type,
+                            bool last_field)
    {
       assert(this->index < this->num_variables);