Set GOPATH and PATH in Makefile
Set GOPATH and PATH in Makefile

The change adds a bit of logic in Makefile to automatically set GOPATH and
prepend GOPATH/bin to PATH.

vaibhavarora/cockroach,arjun4084346/cockroach,nieyy/cockroach,bg451/cockroach,glycerine/cockroach,vivekmenezes/cockroach,sunya123/cockroach,il9ue/cockroach,paperstreet/cockroach,maxlang/cockroach,arjun4084346/cockroach,nieyy/cockroach,sunya123/cockroach,vaibhavarora/cockroach,nieyy/cockroach,petermattis/cockroach,cockroachdb/cockroach,cockroachdb/cockroach,petermattis/cockroach,arjun4084346/cockroach,bg451/cockroach,bg451/cockroach,arjun4084346/cockroach,veteranlu/cockroach,vaibhavarora/cockroach,petermattis/cockroach,il9ue/cockroach,nieyy/cockroach,il9ue/cockroach,glycerine/cockroach,maxlang/cockroach,bg451/cockroach,nieyy/cockroach,il9ue/cockroach,arjun4084346/cockroach,bg451/cockroach,vaibhavarora/cockroach,veteranlu/cockroach,petermattis/cockroach,nieyy/cockroach,maxlang/cockroach,il9ue/cockroach,vaibhavarora/cockroach,maxlang/cockroach,veteranlu/cockroach,vivekmenezes/cockroach,il9ue/cockroach,paperstreet/cockroach,petermattis/cockroach,cockroachdb/cockroach,cuongdo/cockroach,vaibhavarora/cockroach,maxlang/cockroach,il9ue/cockroach,sunya123/cockroach,vivekmenezes/cockroach,arjun4084346/cockroach,cuongdo/cockroach,cuongdo/cockroach,maxlang/cockroach,glycerine/cockroach,il9ue/cockroach,glycerine/cockroach,maxlang/cockroach,arjun4084346/cockroach,petermattis/cockroach,bg451/cockroach,sunya123/cockroach,sunya123/cockroach,veteranlu/cockroach,paperstreet/cockroach,cuongdo/cockroach,sunya123/cockroach,glycerine/cockroach,vivekmenezes/cockroach,cuongdo/cockroach,vivekmenezes/cockroach,petermattis/cockroach,bg451/cockroach,vivekmenezes/cockroach,cuongdo/cockroach,vaibhavarora/cockroach,cuongdo/cockroach,cuongdo/cockroach,paperstreet/cockroach,cockroachdb/cockroach,paperstreet/cockroach,glycerine/cockroach,cockroachdb/cockroach,nieyy/cockroach,paperstreet/cockroach,sunya123/cockroach,glycerine/cockroach,arjun4084346/cockroach,vivekmenezes/cockroach,cockroachdb/cockroach,veteranlu/cockroach,nieyy/cockroach,vivekmenezes/cockroach,paperstreet/cockroach,maxlang/cockroach,glycerine/cockroach,veteranlu/cockroach,petermattis/cockroach,cockroachdb/cockroach,cockroachdb/cockroach,sunya123/cockroach,paperstreet/cockroach,veteranlu/cockroach,veteranlu/cockroach,vaibhavarora/cockroach