I've compiled PHP 4.2.3, patched to work with GD2, as an apache module.  I'm using apache-ssl, and when I try to start it, it gives me the following error:

Starting web server: apache-sslSyntax error on line 243 of /etc/apache-ssl/httpd.conf:
Cannot load /usr/lib/apache/1.3/libphp4.so into server: /usr/lib/apache/1.3/libphp4.so: undefined symbol: xml_utf8_decode
failed

compiled with: ./configure --prefix=/usr --with-regex=php --with-config-file-path=/etc/php4/apache --with-apxs=/usr/bin/apxs --disable-rpath --disable-debug --enable-memory-limit --enable-calendar --enable-sysvsem --enable-sysvshm --enable-track-vars --enable-trans-sid --enable-bcmath --with-bz2 --enable-ctype --with-db2 --with-iconv --with-ndbm --enable-exif --enable-filepro --enable-ftp --with-gettext --enable-mbstring --with-pcre-regex=/usr --enable-shmop --enable-sockets --enable-wddx --with-xml=/usr --with-expat-dir=/usr --enable-yp --with-zlib --without-pgsql --disable-static --with-layout=GNU --with-curl=shared,/usr --with-dom=shared,/usr --with-zlib-dir=/usr --with-gd=shared,/usr --with-jpeg-dir=shared,/usr --with-png-dir=shared,/usr --with-freetype-dir=shared,/usr --with-ldap=shared,/usr --with-mcal=shared,/usr --with-mhash=shared,/usr --with-mm --with-mysql=shared --without-unixODBC --with-recode=shared,/usr --enable-xslt --with-xslt-sablot=shared,/usr --with-snmp=shared --enable-ucd-snmp-hack --without-sybase-ct --with-ttf=shared,/usr --with-t1lib=shared,/usr