[sys-kernel/linux] fix IUSE; add slot version
[virtual] add linux-sources
[sys-kernel/linux] 3.17.4 add in RDEPEND sys-kernel/linux-firmware
[sys-kernel/linux] 3.17.4 change ewarn message
[sys-kernel/linux] add compression modules with gzip and xz
[sys-kernel/linux] 3.17.4 little ewarn changes
[sys-kernel/linux] change copyright
[sys-kernel/linux] bump version to 3.17.6