I got SEGFAUL (signal 11) with this code:
main.php :
<?php
include('inc1.php');
include('inc2.php');
echo $data;
?>
inc1.php :
<?php
define(INCLUDED_INC1,1);
function foo() {
        $return = "return of function foo in inc1.php";
        return $return;
}
?>
inc2.php :
<?php
define(INCLUDED_INC2,1);
if(INCLUDED_INC1)
        $data = foo();
?>

I have configured my php with:
'./configure' '--with-zlib' '--with-zlib-dir=/usr' '--with-snmp' '--enable- mysql' '--enable-sockets' '--prefix=/usr' '--with-apxs=/usr/local/bin/apxs' '--with-regex=php' '-- enable-calendar' '--enable-ftp' '--enable-exif' '--enable-png' '--with-gd'

Debugger output is:
#0  0x400f5bdd in free () from /lib/libc.so.6
#1  0x400f5aa3 in free () from /lib/libc.so.6
#2  0x402d7ecd in shutdown_memory_manager (silent=0, clean_cache=0) at /root/php-4.3.2RC1/Zend/zend_alloc.c:466
#3  0x402be570 in php_request_shutdown (dummy=0x0) at /root/php-4.3.2RC1/main/main.c:1004
#4  0x402ff4f3 in apache_php_module_main (r=0x833a0ec, display_source_mode=0) at /root/php-4.3.2RC1/sapi/apache/sapi_apache.c:61
#5  0x4030009e in send_php (r=0x833a0ec, display_source_mode=0, filename=0x0) at /root/php-4.3.2RC1/sapi/apache/mod_php4.c:617
#6  0x40300102 in send_parsed_php (r=0x833a0ec) at /root/php-4.3.2RC1/sapi/apache/mod_php4.c:632
#7  0x0806b7d9 in ap_invoke_handler ()
#8  0x0808137f in process_request_internal ()

Thanks in advance.