-sys/lib/libkern builds as library per default (as it was documented all
the time)
-ports able to LKM set "KERN_AS=obj" explicitely in their Makefiles
(for now; should depend on actual "option LKM" or -better- functions
included for LKM use should be pulled in by a stub)
-always link libcompat before libkern - libkern stuff can be referred to
by libcompat, but not the other way