.hgignore: add comment setting policy
.hgignore: add comment setting policy

R=golang-codereviews, rsc
CC=golang-codereviews
https://golang.org/cl/44830043

ScriptRock/crypto,cmars/tools,conseweb/golangcrypto,CodyGuo/crypto,cheffo/crypto,cmars/tools,guaiguaihw/crypto,zj8487/crypto,kim-racktop/crypto,cmars/tools,mattharden/crypto,thomaso-mirodin/crypto,thomaso-mirodin/crypto,juniorz/crypto,tca/crypto,pki-io/crypto,cheffo/crypto,cmars/tools,juniorz/crypto,kim-racktop/crypto,progrium/crypto,tca/crypto,CodyGuo/crypto,golang/crypto,pki-io/crypto,conseweb/golangcrypto,Carrotman42/crypto,ScriptRock/crypto,golang/crypto,mattharden/crypto,bford/golang-x-crypto,zj8487/crypto,bford/golang-x-crypto,lucevers/crypto,wooutl/golangcrypto,a-palchikov/crypto,lucevers/crypto,Carrotman42/crypto,a-palchikov/crypto,golang/crypto,wooutl/golangcrypto,progrium/crypto,guaiguaihw/crypto