Silence error messages of cd to non-existent opt directories

configure.ac

@@ -1006,7 +1006,7 @@ AS_IF([test "x$OPT_DIR" != x], [
     save_IFS="$IFS" IFS="$PATH_SEPARATOR" val= PWD=
     for dir in $OPT_DIR; do
         test -z "$dir" && continue
-        dir=`eval $CHDIR '"$dir"' && pwd` || continue
+        dir=`eval $CHDIR '"$dir"' 2>/dev/null && pwd` || continue
         val="${val:+$val$PATH_SEPARATOR}$dir"
     done
     IFS="$save_IFS" OPT_DIR="$val"