owut: exit immediately on ctrl-c

If the user attempted to abort processing during a build, owut
would terminate a subprocess in many cases and then continue with
top-level processing.  We now simply exit the top-level when a user
interrupt signal is detected.

Signed-off-by: Eric Fahlgren <[email protected]>

files/owut

@@ -2066,6 +2066,8 @@ initialize_urls();
 let updates;
 let exit_status = EXIT_ERR;   // Assume failure, until we know otherwise.
 
+signal("SIGINT", exit);  // Ensure ctrl-C works when inside build loop.
+
 switch (options.command) {
 	case "versions":
 		collect_overview();