[eclass] sabayon-kernel: introduce K_KERNEL_NEW_VERSIONING support

K_KERNEL_NEW_VERSIONING=1 makes possible to use the real PV in packages.
[eclass] sabayon-kernel: add sys-devel/autoconf to DEPEND, required by open-iscsi genkernel setup
[sys-kernel/linux-hardened] version bump to 3.7.1
[kde-base/kdm] version bump to 4.9.5
[kde-base/oxygen-icons] version bump to 4.9.5
[eclass] sabayon-kernel: always drop /usr/lib/debug