* 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.
New, from fileutils 4.0.37.
* configure.in: Require Autoconf 2.49c. I took some time before
making this decision. This is the only way out for portability
issues in Bison, it would mean way too much duplicate effort to
import in Bison features implemented in 2.49c since 2.13.
AC_REPLACE_FUNCS and AC_CHECK_DECLS the functions above.
