(This is not actually Sablotron extension bug, but I need to use --with-iconv option for my system to build in Sablotron and have a problem in this case)

1. The error message during Apache restart:
Cannot load /usr/libexec/apache/libphp4.so into server: /usr/libexec/apache/libphp4.so: undefined symbol: iconv_module_entry

2. Configure line:
--with-apxs --prefix=/usr --with-gd --with-gettext --with-yp --with-system-regex --with-mysql=/usr --enable-safe-mode --enable-sysvsem --enable-sysvshm --with-exec-dir=/home/httpd/php/bin --with-zlib --with-config-file-path=/etc/httpd --disable-debug --enable-magic-quotes --enable-bcmath --with-mod_charset --enable-calendar --with-iconv --with-sablot

3. Short description
The configure script and compilation go smoothly without errors. ldd libphp4.so shows the following:
        libpam.so.0 => /lib/libpam.so.0 (0x2abda000)
        libdl.so.2 => /lib/libdl.so.2 (0x2abe1000)
        libz.so.1 => /usr/lib/libz.so.1 (0x2abe5000)
        libexpat.so.0 => /usr/lib/libexpat.so.0 (0x2abf3000)
        libsablot.so.0 => /usr/lib/libsablot.so.0 (0x2ac12000)
        libmysqlclient.so.6 => /usr/lib/libmysqlclient.so.6 (0x2ac8e000)
        libiconv.so.2 => /usr/lib/libiconv.so.2 (0x2aca0000)
        libttf.so.2 => /usr/lib/libttf.so.2 (0x2ad39000)
        libgd.so.1 => /usr/lib/libgd.so.1 (0x2ad4e000)
        libresolv.so.2 => /lib/libresolv.so.2 (0x2ad85000)
        libm.so.6 => /lib/libm.so.6 (0x2ad94000)
        libcrypt.so.1 => /lib/libcrypt.so.1 (0x2adad000)
        libnsl.so.1 => /lib/libnsl.so.1 (0x2addb000)
        libc.so.6 => /lib/libc.so.6 (0x2ade2000)
        /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x2aaab000)
,so all libraries are in place.
But the error message occurs during apache start/restart (see item 1.)

Looking through main/php_config.h I found that there is no line

#define HAVE_ICONV 1

,but if I install it manually I have the following errors during compilation:

make[3]: Entering directory `/mnt/files/linux/www/php/php-4.0.5/ext/iconv'
/bin/sh /mnt/files/linux/www/php/php-4.0.5/libtool --silent --mode=compile gcc  -I. -I/mnt/files/linux/www/php/php-4.0.5/ext/iconv -I/mnt/files/linux/www/php/php-4.0.5/main -I/mnt/files/linux/www/php/php-4.0.5 -I/usr/include/apache -I/mnt/files/linux/www/php/php-4.0.5/Zend -I/usr/include/mysql -I/mnt/files/linux/www/php/php-4.0.5/ext/xml/expat/xmltok -I/mnt/files/linux/www/php/php-4.0.5/ext/xml/expat/xmlparse -I/mnt/files/linux/www/php/php-4.0.5/TSRM  -DLINUX=2 -DEAPI -DKEAPI -DUSE_PERL_SSI -D_REENTRANT -DSUPPORT_UTF8 -DXML_BYTE_ORDER=12 -g -O2  -c iconv.c
iconv.c:59: `php_minit_iconv' undeclared here (not in a function)
iconv.c:59: initializer element for `iconv_module_entry.module_startup_func' is not constant
iconv.c:60: `php_mshutdown_iconv' undeclared here (not in a function)
iconv.c:60: initializer element for `iconv_module_entry.module_shutdown_func' is not constant
iconv.c:63: `php_info_iconv' undeclared here (not in a function)
iconv.c:63: initializer element for `iconv_module_entry.info_func' is not constant
make[3]: *** [iconv.lo] Error 1

So, there is no way to build working PHP4.0.5 with support of external libiconv (outside of glibc, glibc-2.0.7 doesn't have iconv functions). PHP4.0.4pl1 was built and run successfully on the same system with the same configuration options.