Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

the NO_PAM option has been finally removed in favor of WITHOUT_PAM.

add some modern stuff: SMP, SCHED_ULE, PREEMPTION
and support for VIMAGE

Remove libulog from the bootstrap again.

libulog now only provides functions that are used by various packages
from the ports tree, namely the libutempter ones. There is no reason to
link it into the crunch/fixit binaries anymore.

add a 'qemu' floppy type, useful for running tests on new kernels