Add support AMD processors with the SVM/AMD-V hardware extensions.

MFC r273749
Remove bhyve SVM feature printf's now that they are available in the general
CPU feature detection code.

MFC r273766
Add missing 'break' pointed out by Coverity CID 1249760.

MFC r276098
Allow ktr(4) tracing of all guest exceptions via the tunable "hw.vmm.trace_guest_exceptions"

MFC r276392
Inject #UD into the guest when it executes either 'MONITOR' or 'MWAIT' on an
AMD/SVM host.

MFC r276402
Remove "svn:mergeinfo" property that was dragged along when these files were
svn copied in r273375.