modprobe: add -D option (synonym of --show-depends)

modprobe: add -D option (synonym of --show-depends)

The modern module-init-tools 3.12 has "-D" option and it works.

The --show-depends and -a options can be used together due to upstream modprobe
behaviour.

function                                             old     new   delta
do_modprobe                                          536     579     +43
packed_usage                                       28035   28042      +7
modprobe_main                                        653     657      +4
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/0 up/down: 54/0)               Total: 54 bytes

Signed-off-by: Serj Kalichev <serj.kalichev@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>