glsl: add tessellation shader defines and built-in variables.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/glsl/glcpp/glcpp-parse.y

@@ -2486,6 +2486,9 @@ _glcpp_parser_handle_version_declaration(glcpp_parser_t *parser, intmax_t versio
 
 	      if (extensions->ARB_shader_storage_buffer_object)
 	         add_builtin_define(parser, "GL_ARB_shader_storage_buffer_object", 1);
+
+	      if (extensions->ARB_tessellation_shader)
+	         add_builtin_define(parser, "GL_ARB_tessellation_shader", 1);
 	   }
 	}