Proposal for making the kernel packages preserve old copies

[Guido Falsi]

Hi,

I've finally cleaned up a local patch I've been using and sent it as a
code review:

https://reviews.freebsd.org/D17119


As stated in the subject this patch uses a deinstall script to make the
kernel packages copy the kernel directory to kernel.old when
deinstalling. This leaves a fallback kernel on the system when
upgrading, which I find quite useful.

I intentionally made it mimic the "make installkernel" behavior.

I did not add any reviewers in the phabric review since I don't know who
I should ask, but I'd like to get some feedback about this.

Thanks!

-- 
Guido Falsi <madpilot at FreeBSD.org>