os/linux/elf.rb: Use readelf for Linuxbrew (#365)
os/linux/elf.rb: Use readelf for Linuxbrew (#365)

Use readelf if available, otherwise patchelf,
and otherwise print an error.
hanxue/linuxbrew,Linuxbrew/brew,maxim-belkin/brew,maxim-belkin/brew,rwhogg/brew,hanxue/linuxbrew,Linuxbrew/brew,Linuxbrew/brew,hanxue/linuxbrew,rwhogg/brew,Linuxbrew/brew,rwhogg/brew,maxim-belkin/brew