yacc.c, glr.c: check and fix the display of locations

In some case, negative column number could be displayed.
Make YY_LOCATION_PRINT similar to bison's own implementation of
locations.  Since the macro is getting fat, make it a static
function.
Reported by Jonathan Fabrizio.

* data/c.m4 (yy_location_print_define): Improve the implementation,
and generate the yy_location_print_ function.
Adjust YY_LOCATION_PRINT.
* tests/actions.at (Location Print): New tests.

THANKS

@@ -58,6 +58,7 @@ Jim Kent                  [email protected]
 Jim Meyering              [email protected]
 Joel E. Denny             [email protected]
 Johan van Selst           [email protected]
+Jonathan Fabrizio         [email protected]
 Jonathan Nieder           [email protected]
 Juan Manuel Guerrero      [email protected]
 Kees Zeelenberg           [email protected]