xbps-src: simpler way to error in pkgs with only_for_archs.

xbps-src/shutils/tmpl_funcs.sh.in

@@ -289,14 +289,13 @@ prepare_tmpl()
 		fi
 	done
 
-	for i in ${only_for_archs}; do
-		[ "$i" != "$XBPS_MACHINE" ] && continue
-		found=1
-		break
-	done
+	if [ -n "$only_for_archs" ]; then
+		if $(echo "$only_for_archs"|grep -q "$XBPS_MACHINE"); then
+			found=1
+		fi
+	fi
 	if [ -n "${only_for_archs}" -a -z "$found" ]; then
-		msg_normal "$pkgname: this package can only be built on ${only_for_archs}.\n"
-		return 0
+		msg_error "$pkgname: this package cannot be built on $XBPS_MACHINE.\n"
 	fi
 
 	unset XBPS_EXTRACT_DONE XBPS_APPLYPATCHES_DONE