I think that the script configure is broken. I have tried to compile php to enable suporte for sybase DB. But when I enable the option --with-sybase-ct=/usr/local/freeetds the script broke when trying to find zlib 

The error is:
checking for gzgets in -lz... no
configure: error: Zlib module requires zlib >= 1.0.9.

If I remove the option --with-sybase-ct, everything goes well to the end.

I have tried even with the latest version from CVS.





The options that I use are:

./configure --prefix=/usr --with-apxs=/usr/bin/apxs --with-regex=system --with-config-file-path=/etc/php4/apache --enable-calendar --with-db --without-dom --enable-filepro --enable-ftp --with-gettext --enable-sysvsem --enable-sysvshm --enable-track-vars --enable-trans-sid --disable-debug --disable-static --with-gd=shared --with-imap=shared --with-ldap=shared,/usr --with-mm --with-mhash=shared --with-mysql=shared,/usr --with-regex=system --with-pcre-regex=/usr --with-pgsql=shared,/usr --with-snmp=shared --enable-sockets --with-ttf --enable-freetype-4bit-antialias-hack --with-t1lib --with-xml=shared,/usr --with-yp --with-zlib --with-sybase-ct=/usr/local/freetds






The last lines of config.log that maybe of interest:
tail -50 config.log 
#line 41799 "configure"
#include "confdefs.h"

#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
   
int main() {
union semun x;
; return 0; }
configure:41845: checking whether to enable System V shared memory support
configure:42033: checking whether to enable WDDX support
configure:42232: checking whether byte ordering is bigendian
configure:42250: gcc -c -g -O2  -DEAPI conftest.c 1>&5
configure:42265: gcc -c -g -O2  -DEAPI conftest.c 1>&5
configure: In function `main':
configure:42260: `not' undeclared (first use in this function)
configure:42260: (Each undeclared identifier is reported only once
configure:42260: for each function it appears in.)
configure:42260: parse error before `big'
configure: failed program was:
#line 42254 "configure"
#include "confdefs.h"
#include <sys/types.h>
#include <sys/param.h>
int main() {

#if BYTE_ORDER != BIG_ENDIAN
 not big endian
#endif
; return 0; }
configure:42331: checking for XML support
configure:42742: checking for YAZ support
configure:43092: checking whether to include YP support
configure:43289: checking whether to include zlib support
configure:43490: checking for gzgets in -lz
configure:43509: gcc -o conftest -g -O2  -DEAPI -DXML_BYTE_ORDER=12 -L/usr/lib  -Wl,-rpath,/usr/local/freetds/lib -L/usr/local/freetds/lib conftest.c -lz  -lsybtcl -lintl -lcomn -lct -lcs -lmm -lpcre -lt1 -lz -lpng -lresolv -lm -ldl -lcrypt -lnsl  -lresolv 1>&5
/usr/bin/ld: cannot find -lsybtcl
collect2: ld returned 1 exit status
configure: failed program was:
#line 43498 "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 gzgets();

int main() {
gzgets()
; return 0; }