busybox

applets/install: accept more than one install option

Currently, it is impossible to pass more than one option to the isntall
script, so it totally prevents using --noclobber.

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>