Freebsd and postgresql 748: pg_dump compile error

Hi,

I have an error when postgresql compile with flag :

./configure --prefix=/usr/local/postgres --enable-thread-safety

make
...
gcc -O2 -fno-strict-aliasing -Wall -Wmissing-prototypes
-Wmissing-declarations -I../../../src/interfaces/libpq
-I../../../src/include -DBINDIR=\"/usr/local/postgres/bin\" -c -o
dumputils.o dumputils.c
gcc -O2 -fno-strict-aliasing -Wall -Wmissing-prototypes
-Wmissing-declarations pg_dump.o common.o pg_backup_archiver.o
pg_backup_db.o pg_backup_custom.o pg_backup_files.o pg_backup_null.o
pg_backup_tar.o dumputils.o ../../../src/backend/parser/keywords.o
-L../../../src/interfaces/libpq -lpq -L../../../src/port
-R/usr/local/postgres/lib -lz -lreadline -lcrypt -lcompat -lm -lutil
-lpgport -o pg_dump
../../../src/interfaces/libpq/libpq.so: undefined reference to
`pthread_mutex_unlock'
../../../src/interfaces/libpq/libpq.so: undefined reference to
`pthread_mutex_lock'
gmake[3]: *** [pg_dump] Error 1
gmake[3]: Leaving directory `/var/tmp/postgresql-7.4.8/src/bin/pg_dump'
gmake[2]: *** [all] Error 2
gmake[2]: Leaving directory `/var/tmp/postgresql-7.4.8/src/bin'
gmake[1]: *** [all] Error 2
gmake[1]: Leaving directory `/var/tmp/postgresql-7.4.8/src'
gmake: *** [all] Error 2
*** Error code 2

Stop in /var/tmp/postgresql-7.4.8.

Compile error on pg_dump?

Regards
Rmkml