compile error on slackware 9.0 while --enable-thread-safety

while remove --enable-thread-safety everything ok.
what's the matter?
the error output:
---------------------------8<-------------------------------------------------------------
make[2]: Entering directory `/usr/laser/postgresql-7.4beta1/src/port'
gcc -O2 -g -Wall -Wmissing-prototypes -Wmissing-declarations
-I../../src/include   -c -o path.o path.c
gcc -O2 -g -Wall -Wmissing-prototypes -Wmissing-declarations
-I../../src/include   -c -o threads.o threads.c
threads.c: In function `pqGetpwuid':
threads.c:49: too few arguments to function `getpwuid_r'
threads.c:49: warning: assignment makes pointer from integer without a cast
threads.c: In function `pqGethostbyname':
threads.c:74: warning: passing arg 5 of `gethostbyname_r' from
incompatible pointer type
threads.c:74: too few arguments to function `gethostbyname_r'
threads.c:74: warning: assignment makes pointer from integer without a cast
---------------------------8<-------------------------------------------------------------

Thanks and regards

Laser