Openspades: Setting language as "system default" crashes OpenSpades in Windows 10

[feikname]

Version: 0.1.0 _(development)_
Operating System: Windows 10

Steps to reproduce:

• Launch OpenSpades with startup window enable (cl_startupWindow: 1)
• Go to "general" tab
• Set language as "System Default"
• Crashes

Expected behaviour:

• Don't display the option for Windows systems, as it seems to be not supported; OR
• Deal with the error and display it to the user

Crash dump:
https://www.dropbox.com/s/cbjj2behh0kasvs/OpenSpadesCrash29057218.dmp?dl=0

SystemMessages.log:
I didn't include it because it does not contain any useful information for this issue.

Additional information:

• My environment is Windows 10 with English as default language.

[yvt]

According to the debugger message, this might have been caused by a calling convention mismatch.

[mschlumpp]

What about declaring GetUserDefaultLocaleName as __stdcall?