The error below is now fixed.  The problem was that on the Sun3
I tried to keep as many things as possible private to the kernel,
and the structure pmap_physseg is now needed in userland, so the
arch/sun3/include headers now have to export that.

I wish there were fewer kernel data structures exported to
user-level code...

Erik E. Fair writes:
 > cc -O2 -DALL_STATE  -Wall -Wstrict-prototypes -Wmissing-prototypes
 > -Wpointer-arith -Werror   -D_LIBC -DNLS -DYP -DHESIOD -DLIBC_SCCS
 > -DSYSLIBC_SCCS  -D_REENTRANT -I/usr/src/lib/libc/include
 > -D__DBINTERFACE_PRIVATE -DRESOLVSORT -I. -DPOSIX_MISTAKE -DFLOATING_POINT
 > -nostdinc -idirafter /altroot/usr/include -c
 > /usr/src/lib/libc/compat-43/gethostid.c
 > In file included from /altroot/usr/include/vm/vm_object.h:74,
 >                  from /altroot/usr/include/vm/vm.h:83,
 >                  from /altroot/usr/include/sys/sysctl.h:51,
 >                  from /usr/src/lib/libc/compat-43/gethostid.c:48:
 > /altroot/usr/include/vm/vm_page.h:250: field `pmseg' has incomplete type
 > *** Error code 1
 > 
 > Stop.