Rollup merge of #46330 - SimonSapin:patch-6, r=kennytm
Rollup merge of #46330 - SimonSapin:patch-6, r=kennytm

Update comment on alternate builds in .travis.yml

https://github.com/rust-lang/rust/pull/45810#issuecomment-347257640

graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,GBGamer/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,graydon/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,aidancully/rust