ipv6 build error?

On FreeBSD/Alpha:

gmake[3]: Entering directory `/home/chriskl/pgsql-head/src/backend/libpq'
gcc -pipe -O -g -Wall -Wmissing-prototypes -Wmissing-declarations -I../../..
/src/include -c -o be-fsstubs.o be-fsstubs.c -MMD
gcc -pipe -O -g -Wall -Wmissing-prototypes -Wmissing-declarations -I../../..
/src/include -c -o be-secure.o be-secure.c -MMD
gcc -pipe -O -g -Wall -Wmissing-prototypes -Wmissing-declarations -I../../..
/src/include -c -o auth.o auth.c -MMD
gcc -pipe -O -g -Wall -Wmissing-prototypes -Wmissing-declarations -I../../..
/src/include -c -o crypt.o crypt.c -MMD
gcc -pipe -O -g -Wall -Wmissing-prototypes -Wmissing-declarations -I../../..
/src/include -c -o hba.o hba.c -MMD
gcc -pipe -O -g -Wall -Wmissing-prototypes -Wmissing-declarations -I../../..
/src/include -c -o ip.o ip.c -MMD
ip.c: In function `convSockAddr6to4':
ip.c:368: structure has no member named `s6_addr32'
gmake[3]: *** [ip.o] Error 1
gmake[3]: Leaving directory `/home/chriskl/pgsql-head/src/backend/libpq'
gmake[2]: *** [libpq-recursive] Error 2
gmake[2]: Leaving directory `/home/chriskl/pgsql-head/src/backend'
gmake[1]: *** [install] Error 2
gmake[1]: Leaving directory `/home/chriskl/pgsql-head/src'
gmake: *** [install] Error 2

I seem to remember seeing this before when we had some ipv6 code that we
decided to remove in the end...

Chris