protobuf@2.6: update 2.6.1 bottle for Linuxbrew.
protobuf@2.6: update 2.6.1 bottle for Linuxbrew.

rwhogg/homebrew-core,maxim-belkin/homebrew-core,LinuxbrewTestBot/homebrew-core,Linuxbrew/homebrew-core,LinuxbrewTestBot/homebrew-core,maxim-belkin/homebrew-core,rwhogg/homebrew-core,Linuxbrew/homebrew-core