The kernel source is being moved into the sysroot, to do this and
preserve previous builds, we need to change the TMPDIR ABI and
provide a function to uninstall all kernels from the sysroot.
This change adds code to do that and increases the ABI number.
(From OE-Core rev: 323f9ea99cff00a751e446286bf8bcf8756e4351)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>