Build: configure: announce support of "free form" date/time spec support

Now that all compiled CLI tools supporting date/time inputs are
adjusted to support that, and since it's rather platfom specific, care
to advertise the support by standard means.

configure.ac

@@ -902,6 +902,8 @@ AC_SUBST([SUPPORT_DATE_VERSATILITY],
          [$HAVE_date_versatility])
 AM_CONDITIONAL([BUILD_DATE_VERSATILITY],
                [test $HAVE_date_versatility = 1])
+test x"$HAVE_date_versatility" = x0 \
+  || PCMK_FEATURES="$PCMK_FEATURES date-versatility"
 
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