Test cmd_execute with negative exit code

[WangWeiLin-MV]

Add test program closes-exit-int-min.c to return exit code with negative value -1, expected -1 for windows, expected 255 for unix.

Failed as expected before #1489

[WangWeiLin-MV]

Duplicate of 1489

[BillyONeal]

I think your test idea is good; if you want to fix it to do TerminateProcess(GetCurrentProcess(), 0xC0000000); instead of trying to return from main that would be much appreciated. But no need to do that if you don't want.

[BillyONeal]

Thanks so much for the test! <3

[BillyONeal]

Thanks for the test!