When compiling a cgi-sapi PHP, md5 crypt() function (although detected by configure) is disabled in the final linked php binary when openssl is used (either --with-openssl or --with-imap-ssl).  My guess is that because -lcrypt is used after -lcrypto when linking the php binary, the crypt() function is taken out of openssl and not the system.  A reordering of the libraries should fix this, although I haven't tried.

CONFIGURATION:

./configure \
  --with-imap=/usr/local/devel/c-client \
  --with-imap-ssl=/usr/local/security/openssl \
  --enable-discard-path

...

checking for standard DES crypt... (cached) yes
checking for extended DES crypt... (cached) no
checking for MD5 crypt... (cached) yes

...

SCRIPT:

<?php echo crypt('word', '$1$12345678$'); ?>

RESULT:

X-Powered-By: PHP/4.2.3
Content-type: text/html

$1uG4BAzM10Ak

...

CONFIGURATION:

./configure \
  --enable-discard-path

SCRIPT:

<?php echo crypt('word', '$1$12345678$'); ?>

RESULT:

X-Powered-By: PHP/4.2.3
Content-type: text/html

$1$12345678$yVbgM2z3.C246JEAhNVQ5/