Configure command used was :

./configure --with-apxs=/opt/apache/bin/apxs --with-pgsql=/opt/postgres --with-pdflib=/opt/pdflib --with-sybase-ct=/opt/sybase

All packages (apache, postgres, pdflib, sybase) all exist in those directories. The configuration works and the compile reaches the final link, but gives :

collect2: ld terminated with signal 11 [Segmentation fault]
make[1]: *** [libphp4.la] Error 1
make[1]: Leaving directory `/opt/php-4.0.0'
make: *** [all-recursive] Error 1

The compile succeeds if sybase is left out.