MFC r257650:

Defer loading of kernel and modules if the beastie menu is enabled. Add a
kernel selection menu to the beastie menu. List of kernels is taken from
`kernels' in loader.conf(5) as a space (or comma) separated list of names
to display (up to 9). If not set, default value is "kernel kernel.old".
Does not validate that kernels exist because the next enhancement will be
to allow selection of the root device.

Discussed on:	-current
MFC r257821:

Extend loader_delay as-documented in beastie.4th(8) and delay.4th(8),
making it available to architectures that do not use or load the beastie
menu. This is reported to save headaches on some PPC systems where unload
followed by load does not produce the desired results wherein if-given
the opportunity to abort the initial loading sequence, you can customize
the first load.

Reviewed by:	nwhitehorn, kan
Discussed on:	-current