Add two variables to adjust where to install kernel and modules.
DESTLABEL common suffix added to kernel and modules directory. for
example, `make DESTLABEL=test installkernel' installs them
as /boot/kernel.test and /boot/modules.test, respectively.
DESTKERNDIR where to install kernel and modules, /boot by default.
Add /sys/conf/kern.path.mk to define default paths for kernel and modules.
Also move KMOD* definitions to /sys/conf/kmod.mk where it really belongs.
Submitted-by: Stefan Johannesdal <stefan.johannesdal@gmail.com>
with a slight modification by me.