swapon: support "pri=NNN" in fstab

function                                             old     new   delta
swap_on_off_main                                     244     365    +121

Signed-off-by: Tito Ragusa <farmatito@tiscali.it>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
udhcpc: tweak help text

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
udhcpc: tweak help text more

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