Change Win32 ExitProcess to C func exit

[kawaii-ghost]

Calling C runtime function must also terminated by C runtime itself (exit). Calling printf and then call ExitProcess without CRT function leads to hang because that does not let the C runtime terminate as gracefully.

First argument also passed in RCX, RAX is used as return value. Did you mean add rsp, 32; pop rbp; xor eax, eax; ret ?