config: remove starttime in BgpGlobalStateType struct
config: remove starttime in BgpGlobalStateType struct

It's not used. We'll add again when it'll become necessary. This is
part of work to remove time.Time in bgp_config.go since no nice way to
represent time.Time with yang.

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

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