I'm using Apache 1.3.19 (with so-module of course), mhash-0.8.9, libmcrypt-2.4.9, mcrypt-2.5.5 (last three in packages)
php configure line:
./configure --prefix=/usr/local/php4 --with-apxs=/usr/local/apache/bin/apxs --with-mysql --with-pgsql --with-mcrypt --with-mhash
configuring finish succesfully, but in config.log I can find this messages:
configure:23001: checking for init_mcrypt in -lmcrypt
configure:23020: gcc -o conftest -g -O2  -DLINUX=22 -DUSE_HSREGEX -DUSE_EXPAT  -Wl,-rpath,/usr/local/lib -L/usr/local/lib conftest.c -lmcrypt  -lresolv -lm -ldl -lcrypt -lnsl  -lresolv 1>&5
/usr/local/lib/libmcrypt.so: undefined reference to `lt_dlerror'
/usr/local/lib/libmcrypt.so: undefined reference to `lt_dlclose'
/usr/local/lib/libmcrypt.so: undefined reference to `lt_dlexit'
/usr/local/lib/libmcrypt.so: undefined reference to `lt_dlsetsearchpath'
/usr/local/lib/libmcrypt.so: undefined reference to `lt_dlopenext'
/usr/local/lib/libmcrypt.so: undefined reference to `lt_dlsym'
/usr/local/lib/libmcrypt.so: undefined reference to `lt_dlinit'
collect2: ld returned 1 exit status
configure: failed program was:
#line 23009 "configure"
#include "confdefs.h"
/* Override any gcc2 internal prototype to avoid an error.  */
/* We use char because int might match the return type of a gcc2
    builtin and then its argument prototype would still apply.  */
char init_mcrypt();

int main() {
init_mcrypt()
; return 0; }
configure:23050: checking for mcrypt_module_open in -lmcrypt
configure:23069: gcc -o conftest -g -O2  -DLINUX=22 -DUSE_HSREGEX -DUSE_EXPAT  -Wl,-rpath,/usr/local/lib -L/usr/local/lib conftest.c -lmcrypt  -lresolv -lm -ldl -lcrypt -lnsl  -lresolv -lltdl 1>&5
configure:23357: checking for mhash support
configure:23683: checking for mSQL support

(I tried to be so short as possible).
But I can compile PHP succesfully. When I try to encrypt and decrypt some values this values are diffrent before and after decrypting. E.g:
$login should be eqaul mcrypt_cfb($code_method, $code_key, mcrypt_cfb($code_method, $code_key, $login, MCRYPT_ENCRYPT), MCRYPT_DECRYPT);
but it isn't :-((
What else ??? Various browsers in another way show this value. If I try to do:
  $login = "sydney"
  print $login . "Hello"
links shows as: "sydney..Hello"
Netscape 4.76 as: "sydney" and i can't print anything else.
strlen($login) always is equal 8.