Avoid collisions between parallel installations of Cygwin

[Christian Franke]

Corinna Vinschen wrote:

> --- cygwin/external.cc	6 Oct 2009 21:51:16 -0000	1.108
> +++ cygwin/external.cc	12 Oct 2009 16:02:18 -0000
> @@ -413,6 +413,12 @@ cygwin_internal (cygwin_getinfo_types t,
>  	  int useTerminateProcess = va_arg (arg, int);
>  	  exit_process (status, !!useTerminateProcess); /* no return */
>  	}
> +      case CW_GET_INSTKEY:
> +	{
> +	  extern WCHAR installation_key_buf[18];
> +	  PWCHAR dest = va_arg (arg, PWCHAR);
> +	  wcscpy (dest, installation_key_buf);
> +	}
>  
>        default:
>  	break;
>   

Minor issue: 'return 0;' missing.

Christian