Regression test fails on Solaris 9 for 7.4.2

I've compiled and regression-tested 7.4.2 on Solaris 8 without
trouble. But I'm having some issues with the same release on
Solaris 9. It won't compile with gcc (3.0.4).
Config.log tells me:

configure:7204: gcc -c -O2 -fno-strict-aliasing -I/usr/local/include conftest.c >&5
In file included from /usr/include/netinet/in.h:41,
from /usr/include/sys/socket.h:199,
from configure:7232:
/usr/include/sys/stream.h:307: parse error before "projid_t"

With Sun's cc (Workshop 5.0), it does compile, but the regression test
fails while vacuuming the temporary installation, with a "bad system
call" message. The IPC settings are as per the FAQ's recommendations.
I'm not sure where to look, now. If anyone has any insights or
suggestions for me to try I'd be very grateful. Cheers,

Nishad
--
"Underneath the concrete, the dream is still alive" -- Talking Heads