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

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.