Report, if anybody interested.

So far so good, some glitches (I think because of solaris host)
- fixinc.sh tries to access target directory( I used --prefix for
configure ?)
- it was failed to build libgcc2.a, I don't need it so commenting out
LIBGCC2 and LIBGCC2_INSTALL in Makefile worked.

oh, make LANGUAGES=c to avoid a whole bunch.

It looks like what it can't compile sys/lib/kern/sha1.c with
optimization; it run hard for about 5 minutes having all cpu,
then I recompiled it manually.

GENERIC recompiled, but when booted over network it sent ipv6 instead
of rarp request. ?