Smoke test on macos now compiles

tests/smoke/hello_cube/main_macos.mm

@@ -0,0 +1,33 @@
+#import "Cocoa/Cocoa.h"
+#include "kraken.h"
+
+using namespace kraken;
+
+int main(int argc, const char * argv[])
+{
+  @autoreleasepool {
+    [NSApplication sharedApplication];
+
+    //
+    // Create a window:
+    //
+
+    // Style flags:
+    NSUInteger windowStyle = NSTitledWindowMask | NSClosableWindowMask | NSResizableWindowMask;
+
+    NSRect windowRect = NSMakeRect(0, 0, 640, 480);
+    NSWindow * window = [[NSWindow alloc] initWithContentRect:windowRect
+                                          styleMask:windowStyle
+                                          backing:NSBackingStoreBuffered
+                                          defer:NO];
+    [window autorelease];
+
+    // Window controller:
+    NSWindowController * windowController = [[NSWindowController alloc] initWithWindow:window];
+    [windowController autorelease];
+
+    [window orderFrontRegardless];
+    [NSApp run];
+  }
+  return 0;
+}