Cannot build pfil 2.1.6 on Solaris 9 with Sun's C compiler

IP Filter 4.1.9 built fine (64-bit)

but pfil gives these errors when i try to build.

wonko@wiggum$ make
i=`uname -s`; case $i in HP-UX) make hpux;; *) make $i;; esac
make SunOS`optisa sparcv9 >/dev/null 2>&1; if [ $? -eq 0 ] ; then echo
"64"; else echo "32"; fi`
(cd SunOS; make pfil "BITS=32" OS=solaris DO=pfil "ADEF=-I.. -I.
-D_KERNEL -DSUNDDI -DSOLARIS2="`uname -r | sed -e
's/[0-9]*\.\([0-9]*\).*/\1/'`" -DPFILDEBUG")
cc -fast -xtarget=ultra2i -xarch=v9a -I/usr/local/include -I.. -I.
-D_KERNEL -DSUNDDI -DSOLARIS2=9 -DPFILDEBUG -c ../pfil.c -o pfil.o
"/usr/include/iso/signal_iso.h", line 48: identifier redeclared: signal
current : function(int, pointer to function(..) returning void)
returning pointer to function(int) returning void
previous: function(int, int) returning void :
"/usr/include/sys/proc.h", line 486
"/usr/include/signal.h", line 77: identifier redeclared: sigsendset
current : function(pointer to const struct procset {enum idop
{POP_XOR(3), POP_OR(2), POP_AND(1), POP_DIFF(0)} p_op, enum idtype
{P_PROJID(10), P_TASKID(9), P_LWPID(8), P_ALL(7), P_GID(6), P_UID(5),
P_CID(4), P_SID(3), P_PGID(2), P_PPID(1), P_PID(0)} p_lidtype, int
p_lid, enum idtype {P_PROJID(10), P_TASKID(9), P_LWPID(8), P_ALL(7),
P_GID(6), P_UID(5), P_CID(4), P_SID(3), P_PGID(2), P_PPID(1), P_PID(0)}
p_ridtype, int p_rid}, int) returning int
previous: function(pointer to struct procset {enum idop
{POP_XOR(3), POP_OR(2), POP_AND(1), POP_DIFF(0)} p_op, enum idtype
{P_PROJID(10), P_TASKID(9), P_LWPID(8), P_ALL(7), P_GID(6), P_UID(5),
P_CID(4), P_SID(3), P_PGID(2), P_PPID(1), P_PID(0)} p_lidtype, int
p_lid, enum idtype {P_PROJID(10), P_TASKID(9), P_LWPID(8), P_ALL(7),
P_GID(6), P_UID(5), P_CID(4), P_SID(3), P_PGID(2), P_PPID(1), P_PID(0)}
p_ridtype, int p_rid}, pointer to struct {int sig, int perm, int
checkperm, int sicode, union sigval {..} value}) returning int :
"/usr/include/sys/procset.h", line 126
"/usr/include/string.h", line 69: identifier redeclared: ffs
current : function(int) returning int
previous: function(long) returning int :
"/usr/include/sys/systm.h", line 150
"/usr/include/iso/stdarg_iso.h", line 78: warning: macro redefined:
va_start
"/usr/include/iso/stdarg_iso.h", line 117: syntax error before or at:
void
"/usr/include/iso/stdarg_iso.h", line 117: warning: syntax error:
empty declaration
"../pfil.c", line 113: warning: implicit function declaration:
READ_ENTER
"../pfil.c", line 115: warning: implicit function declaration:
mi_mpprintf
"../pfil.c", line 127: warning: implicit function declaration: RW_EXIT
"../pfil.c", line 130: cannot recover from previous errors
cc: acomp failed for ../pfil.c
*** Error code 2
make: Fatal error: Command failed for target `pfil.o'
Current working directory /mail/home/wonko/software/pfil/SunOS
*** Error code 1
make: Fatal error: Command failed for target `SunOS64'
Current working directory /mail/home/wonko/software/pfil
*** Error code 1 (ignored)
wonko@wiggum$

A quick guess is that I'm missing a header file or some such that
READ_ENTER, mi_mpprintf and RW_EXIT aren't getting defined, but as to
what header file that could be? no idea.

wonko@wiggum$ cc -V
cc: Sun C 5.5 2003/03/12
usage: cc [ options] files. Use 'cc -flags' for details
wonko@wiggum$ uname -a
SunOS wiggum.4amlunch.net 5.9 Generic_117171-15 sun4u sparc
SUNW,UltraSPARC-IIi-cEngine
wonko@wiggum$

I tried to find a pre-built package on the internet for pfil, but all I
could find was a 32-bit one, which obviously won't work on a 64-bit OS.
;)

Thanks for the help!

-brian