fixes some namespace pollution in general and breakage of modules that
aren't in the sys tree in particular (<machine/ipl.h> includes further
headers that aren't installed under /usr/include).
Reimplemented SPLASSERT() so that it is more machine independent and
less bloated and doesn't require the <machine/ipl.h> include spam.
In particular, don't assume that `cpl' can be printed using %08x
format. The alpha arch doesn't even have `cpl'. SPLASSERT() was
harmless on alphas because it isn't actually used.
90bb57afd9