make 17 state-changing execing applets (ex: "nice PROG ARGS") noexec

make 17 state-changing execing applets (ex: "nice PROG ARGS") noexec

The applets with "<applet> [opts] PROG ARGS" API very quickly exec
another program, noexec is okay for them:

 chpst/envdir/envuidgid/softlimit/setuidgid
 chroot
 chrt
 ionice
 nice
 nohup
 setarch/linux32/linux64
 taskset
 cttyhack

"reset" and "sulogin" applets don't have this form, but also exec
another program at once, thus made noexec too.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>