Update protobuf to 2.4.1
Update protobuf to 2.4.1

Change-Id: I0274b3209a23bdb4b3863ecc35145046e3138d30

GerritCodeReview/gwtorm,1yvT0s/gerrit.gwtorm,GerritCodeReview/gwtorm,evanchueng/gerrit.gwtorm,CandyShop/gerrit.gwtorm,thinkernel/gwtorm,thinkernel/gwtorm