hiro: prevent exception originating from appkit (#1324)

As noted in the Chromium source, the value for
NSTreatUnknownArgumentsAsOpen needs to be of type string despite being a
boolean setting.

If the type is boolean, AppKit throws an exception (which is caught),
but if unwinding fails (observed on some arm64 systems in certain build
configurations when ares is compiled with LTO and -fomit-frame-pointer)
it terminates the whole application.

I've confirmed the behavior the original commit was designed to correct
is still fixed with this change.

hiro/cocoa/application.cpp

@@ -52,7 +52,8 @@ auto pApplication::run() -> void {
     //[[NSRunLoop currentRunLoop] addTimer:applicationTimer forMode:NSEventTrackingRunLoopMode];
   }
   [[NSUserDefaults standardUserDefaults] registerDefaults:@{
-    @"NSTreatUnknownArgumentsAsOpen": @NO
+    //@"NO" is not a mistake; the value really needs to be a string
+    @"NSTreatUnknownArgumentsAsOpen": @"NO"
   }];
 
   @autoreleasepool {