%expext was not functioning at all.

* src/conflicts.c (expected_conflicts): Set to -1.
(conflict_report): Use ngettext.
(conflicts_print): Check %expect and make its violation an error.
* doc/bison.texinfo (Expect Decl): Adjust.
* configure.in (AM_GNU_GETTEXT): Ask for ngettext.
* tests/regression.at (%expect not enough, %expect right)
(%expect too much): New.

configure.in

@@ -90,12 +90,12 @@ jm_PREREQ_ERROR
 AM_WITH_DMALLOC
 
 ALL_LINGUAS="de es et fr ja nl tr ru"
-AM_GNU_GETTEXT
+AM_GNU_GETTEXT(, need-ngettext)
 
 # This is necessary so that .o files in LIBOBJS are also built via
 # the ANSI2KNR-filtering rules.
-LIBOBJS=`echo $LIBOBJS|sed 's/\.o /\$U.o /g;s/\.o$/\$U.o/'`
-AC_SUBST(LIBOBJS)
+LIB@&t@OBJS=`echo $LIB@&t@OBJS|sed 's/\.o /\$U.o /g;s/\.o$/\$U.o/'`
+AC_SUBST(LIB@&t@OBJS)
 
 AC_OUTPUT([Makefile
            config/Makefile