glr.c: omit yyresolveLocations when locations are disabled.

glr.c: omit yyresolveLocations when locations are disabled.

This prevents gcc 4.6.0's -Wunused-but-set-variable from warning
about yyresolveLocations's local yyrhsloc.  When locations are
enabled, there's no such warning because YYLLOC_DEFAULT then uses
yyrhsloc.  Reported by Jim Meyering at
<http://lists.gnu.org/archive/html/bug-bison/2011-04/msg00002.html>.
* data/glr.c (yyresolveLocations): Omit definition when locations
are disabled.
(yyresolveValue): Omit yyresolveLocations invocation when
locations are disabled.