Unable to build strace-4.5.18 under FreeBSD 6.4

[andrew clarke]

# uname -a
FreeBSD blizzard.phoenix 6.4-RELEASE FreeBSD 6.4-RELEASE #0: Wed Nov 26 11:43:51 UTC 2008     root at dessler.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  i386

# make
===>  Vulnerability check disabled, database not found
===>  Extracting for strace-4.5.18
=> MD5 Checksum OK for strace-4.5.18.tar.bz2.
=> SHA256 Checksum OK for strace-4.5.18.tar.bz2.
===>   strace-4.5.18 depends on file: /usr/local/bin/perl5.8.8 - found
===>  Patching for strace-4.5.18
===>   strace-4.5.18 depends on file: /usr/local/bin/perl5.8.8 - found
===>  Applying FreeBSD patches for strace-4.5.18
/usr/bin/sed -i.bak 's,/usr/bin/perl,/usr/local/bin/perl,' /spare/ports/devel/strace/work/strace-4.5.18/strace-graph
===>   strace-4.5.18 depends on file: /usr/local/bin/perl5.8.8 - found
===>  Configuring for strace-4.5.18

...

===>  Building for strace-4.5.18
make  all-am
cc -DHAVE_CONFIG_H -I. -Ifreebsd/i386 -I./freebsd/i386 -Ifreebsd -I./freebsd    -Wall -O2 -fno-strict-aliasing -pipe -MT strace.o -MD -MP -MF .deps/strace.Tpo -c -o strace.o strace.c
mv -f .deps/strace.Tpo .deps/strace.Po
cc -DHAVE_CONFIG_H -I. -Ifreebsd/i386 -I./freebsd/i386 -Ifreebsd -I./freebsd    -Wall -O2 -fno-strict-aliasing -pipe -MT syscall.o -MD -MP -MF .deps/syscall.Tpo -c -o syscall.o syscall.c
syscall.c: In function `internal_syscall':
syscall.c:719: error: `sys_waitpid' undeclared (first use in this function)
syscall.c:719: error: (Each undeclared identifier is reported only once
syscall.c:719: error: for each function it appears in.)
*** Error code 1

Stop in /spare/ports/devel/strace/work/strace-4.5.18.
*** Error code 1

Regards
Andrew