v3rpc: bytes-key map look-up gc optimization
v3rpc: bytes-key map look-up gc optimization

This change
https://github.com/golang/go/commit/f5f5a8b6209f84961687d993b93ea0d397f5d5bf
just got merged to go1.6.1 where Go does special optimization for x =
m[string(k)] where k is []byte.

OyTao/etcd_learning,ajityagaty/etcd,zaphod-concur/etcd,mkumatag/etcd,ravigadde/etcd,ktateish/etcd,sofuture/etcd,lorneli/etcd,whuwxl/etcd,chipironcin/etcd,fanminshi/etcd,rchicoli/etcd,dannysauer/etcd,chipironcin/etcd,ajityagaty/etcd,StorReduce/etcd,akauppi/etcd,dannysauer/etcd,glycerine/etcd,wantonsolutions/dinv-etcd,OyTao/etcd_learning,linuxcer/etcd,armstrongli/etcd,wantonsolutions/dinv-etcd,achanda/etcd,fanminshi/etcd,a-robinson/etcd,li-ang/etcd,yudai/etcd,rnaveiras/etcd,ktateish/etcd,insequent/etcd,joshix/etcd,etcd-io/etcd,ravigadde/etcd,qqsun8819/etcd,CrazyJvm/etcd,westhood/etcd,bluebreezecf/etcd,akauppi/etcd,bdarnell/etcd,rnaveiras/etcd,handsomesun/etcd,joshix/etcd,visheshnp/etcd,plasticbox/etcd,jlamillan/etcd,zaphod-concur/etcd,glevand/coreos--etcd,heyitsanthony/etcd,glycerine/etcd,mqliang/etcd,lumjjb/etcd,jlamillan/etcd,jonboulle/etcd,rchicoli/etcd,purpleidea/etcd,linuxcer/etcd,jonboulle/etcd,qqsun8819/etcd,coreos/etcd,sebrandon1/etcd,achanda/etcd,cockroachdb/etcd,hongchaodeng/etcd,mqliang/etcd,dnaeon/etcd,etcd-io/etcd,nekto0n/etcd,hongchaodeng/etcd,tguangch/etcd,mickep76/etcd,swingbach/etcd,bluebreezecf/etcd,visheshnp/etcd,sebrandon1/etcd,lumjjb/etcd,sinsharat/etcd,handsomesun/etcd,vimalk78/etcd,armstrongli/etcd,xiang90/etcd,tguangch/etcd,gyuho/etcd,StorReduce/etcd,luxas/etcd,mkumatag/etcd,YuleiXiao/etcd,heyitsanthony/etcd,purpleidea/etcd,gyuho/etcd,dnaeon/etcd,CrazyJvm/etcd,westhood/etcd,wantonsolutions/dinv-etcd,mickep76/etcd,a-robinson/etcd,insequent/etcd,glevand/coreos--etcd,rnaveiras/etcd,nekto0n/etcd,YuleiXiao/etcd,luxas/etcd,sinsharat/etcd,etcd-io/etcd,li-ang/etcd,coreos/etcd,lorneli/etcd,ajityagaty/etcd,plasticbox/etcd,sofuture/etcd,yudai/etcd,endocode/etcd,cockroachdb/etcd,whuwxl/etcd,mqliang/etcd,mkumatag/etcd,xiang90/etcd,bdarnell/etcd,endocode/etcd,swingbach/etcd,vimalk78/etcd