ARM SMP is ready for prime time on FreeBSD

[Ian Lepore]

Thanks to the contributions of many dedicated freebsd-arm hackers over
the past few months, it looks like SMP is now solid enough for everyday
use.  SMP has been "kinda working" for a while, but I think the pmap
fixes we've been working on for the past few weeks have made things
pretty robust.  I've had continuous stress-testing on running on dual
and quad-core boards with a multi-threaded app that maxes out all the
cores with heavy floating point and network IO and haven't had any app
crashes or kernel panics for a couple weeks.

I've updated the kernel configs for the platforms I know have multiple
cores, as of r264138.

-- Ian