Fixed launchUrl on Mac OS X, code by dgough @ github

gameplay/src/PlatformMacOSX.mm

@@ -1887,12 +1887,15 @@ bool Platform::launchUrl(const char *url)
     if (url == NULL || *url == '\0')
         return false;
 
-    CFURLRef cfUrl = CFURLCreateWithString(0, CFSTR(url), 0);
-    if (cfUrl == 0)
-        return false;
-
-    const OSStatus err = LSOpenCFURLRef(cfUrl, 0);
-
+    CFURLRef urlRef = CFURLCreateWithBytes(
+        NULL,
+        (UInt8*)url,
+        strlen(url),
+        kCFStringEncodingASCII,
+        NULL
+    );
+    const OSStatus err = LSOpenCFURLRef(urlRef, 0);
+    CFRelease(urlRef);
     return (err == noErr);
 }