VMS change to temp file handling in gcc.c

[DJ Delorie]

DJ is Ok with this one.

> + #ifdef VMS
> +       fd = open (template, O_RDWR|O_CREAT|O_EXCL, 0600, "mxv=1");
> + #else
>         fd = open (template, O_RDWR|O_CREAT|O_EXCL, 0600);
> + #endif