MainThread checker warning at sdl_handleSystemRequestLaunchApp function

[t-yoshii]

Bug Report

sdl_handleSystemRequestLaunchApp function in SDLProxy.m calls [[UIApplication sharedApplication] openURL], this call can cause warning by Xcode main thread checker because it can be executed other than the main thread.

sdl_handleSystemRequestLaunchApp should be called only in the main thread.

Reproduction Steps

1. Enable “Main Thread Checker” in Xcode, and run application in debug mode.
2. Connect app to HU

3. Make app foreground on HS
   
4. Run app on HU

4. Run another app on HU

5. Observe console log in HS

Expected Behavior

MainThread checker warning is NOT logged.

Observed Behavior

MainThread checker warning is logged.

OS & Version Information

• iOS Version: 13.0
• SDL iOS Version: 6.3.1
• Testing Against: N/A

Test Case, Sample Code, and / or Example App

I will create PR

[NicoleYarroch]

Fixed in PR #1663