fixed bug that overwrites saved stty settings

[Sketch98]

To reproduce the bug, start shfm, resize your terminal to trigger SIGWINCH's trap, then exit shfm. You'll notice that icanon and echo are disabled even though term_reset should've reset those. At program start, stty is saved so that it can be restored at exit. SIGWINCH's trap calls term_setup which overwrites stty unnecessarily. I moved stty set out of term_setup to avoid this.