gobpg: fix global command
gobpg: fix global command

ipv4 should be used if an address family is not specified.

Signed-off-by: FUJITA Tomonori <93dac1fe9c4b2a3957982200319981492ad4976e@lab.ntt.co.jp>

ramrunner/gobgp,fujita/gobgp,fujita/gobgp,h-naoto/gobgp,h-naoto/gobgp,Dipsingh/gobgp,tamihiro/gobgp,a16/gobgp,YujiOshima/gobgp,ishidawataru/gobgp,a16/gobgp,ishidawataru/gobgp,ishidawataru/gobgp,fujita/gobgp,osrg/gobgp,ramrunner/gobgp,YujiOshima/gobgp,Dipsingh/gobgp,a16/gobgp,ramrunner/gobgp,j-kato/gobgp,a16/gobgp,YujiOshima/gobgp,a16/gobgp,fujita/gobgp,tamihiro/gobgp,a16/gobgp,osrg/gobgp,osrg/gobgp,a16/gobgp,j-kato/gobgp,osrg/gobgp,h-naoto/gobgp,j-kato/gobgp,tamihiro/gobgp,tamihiro/gobgp,Dipsingh/gobgp