.travis.yml: Simplify for Linuxbrew
.travis.yml: Simplify for Linuxbrew

hanxue/linuxbrew,hanxue/linuxbrew,rwhogg/brew,maxim-belkin/brew,hanxue/linuxbrew,Linuxbrew/brew,rwhogg/brew,Linuxbrew/brew,maxim-belkin/brew,rwhogg/brew,Linuxbrew/brew,Linuxbrew/brew,maxim-belkin/brew