Description:
------------
Segmentation failed when use ADODB php library. 

Reproduce code:
---------------
<?php
// xdebug_start_trace("/tmp/test5.trace",0);
include('adodb/adodb.inc.php');
                $conn = &ADONewConnection('informix');
        print "THE END\n";
?>

First http request to HTTPD is OK. 
Next requests is fail.


Actual result:
--------------
Backtrace of  /usr/sbin/httpd -X


zend_do_inherit_interfaces (ce=0x2000000808d71f58, iface=Variable "iface" is not available.
) at /usr/src/debug/php-5.1.3RC1/Zend/zend_compile.c:2135
2135            if (!(ce->ce_flags & ZEND_ACC_INTERFACE) && iface->interface_gets_implemented && iface->interface_gets_implemented(iface, ce TSRMLS_CC) == FAILURE) {
(gdb) bt
#0  zend_do_inherit_interfaces (ce=0x2000000808d71f58, iface=Variable "iface" is not available.
) at /usr/src/debug/php-5.1.3RC1/Zend/zend_compile.c:2135
#1  0x2000000801c4f510 in zend_do_inheritance (ce=0x2000000808d71f58, parent_ce=0x2000000808e3d538)
    at /usr/src/debug/php-5.1.3RC1/Zend/zend_compile.c:2200
#2  0x2000000801c500e0 in do_bind_inherited_class (opline=0x2000000806de4d00, class_table=0x2000000802a037f0,
    parent_ce=0x2000000808e3d538, compile_time=Variable "compile_time" is not available.
) at /usr/src/debug/php-5.1.3RC1/Zend/zend_compile.c:2333
#3  0x2000000801ccc520 in ZEND_DECLARE_INHERITED_CLASS_SPEC_HANDLER (execute_data=0x60000fffffff3ad0)
    at /usr/src/debug/php-5.1.3RC1/Zend/zend_vm_execute.h:492
#4  0x2000000801cc8600 in execute (op_array=0x2000000808d728a8) at /usr/src/debug/php-5.1.3RC1/Zend/zend_vm_execute.h:92
#5  0x2000000802a482e0 in xdebug_execute (op_array=0x2000000808d728a8)
    at /usr/src/redhat/BUILD/php-xdebug-5.1.2/xdebug.c:1242
#6  0x2000000801d01af0 in ZEND_INCLUDE_OR_EVAL_SPEC_VAR_HANDLER (execute_data=0x60000fffffff4210)
    at /usr/src/debug/php-5.1.3RC1/Zend/zend_vm_execute.h:7344
#7  0x2000000801cc8600 in execute (op_array=0x2000000808ee2130) at /usr/src/debug/php-5.1.3RC1/Zend/zend_vm_execute.h:92
#8  0x2000000802a482e0 in xdebug_execute (op_array=0x2000000808ee2130)
    at /usr/src/redhat/BUILD/php-xdebug-5.1.2/xdebug.c:1242
#9  0x2000000801cc8cd0 in zend_do_fcall_common_helper_SPEC (execute_data=0x60000fffffff6130)
    at /usr/src/debug/php-5.1.3RC1/Zend/zend_vm_execute.h:234
#10 0x2000000801cc8600 in execute (op_array=0x2000000808ee23d0) at /usr/src/debug/php-5.1.3RC1/Zend/zend_vm_execute.h:92
#11 0x2000000802a482e0 in xdebug_execute (op_array=0x2000000808ee23d0)
    at /usr/src/redhat/BUILD/php-xdebug-5.1.2/xdebug.c:1242
#12 0x2000000801cc8cd0 in zend_do_fcall_common_helper_SPEC (execute_data=0x60000fffffff7580)
    at /usr/src/debug/php-5.1.3RC1/Zend/zend_vm_execute.h:234
#13 0x2000000801cc8600 in execute (op_array=0x2000000808c2a1b8) at /usr/src/debug/php-5.1.3RC1/Zend/zend_vm_execute.h:92
#14 0x2000000802a482e0 in xdebug_execute (op_array=0x2000000808c2a1b8)
    at /usr/src/redhat/BUILD/php-xdebug-5.1.2/xdebug.c:1242
#15 0x2000000801cd8c30 in ZEND_INCLUDE_OR_EVAL_SPEC_CONST_HANDLER (execute_data=0x60000fffffff8530)
    at /usr/src/debug/php-5.1.3RC1/Zend/zend_vm_execute.h:1926
#16 0x2000000801cc8600 in execute (op_array=0x2000000808f14bb8) at /usr/src/debug/php-5.1.3RC1/Zend/zend_vm_execute.h:92
#17 0x2000000802a482e0 in xdebug_execute (op_array=0x2000000808f14bb8)
    at /usr/src/redhat/BUILD/php-xdebug-5.1.2/xdebug.c:1242
#18 0x2000000801c80d90 in zend_execute_scripts (type=Variable "type" is not available.
) at /usr/src/debug/php-5.1.3RC1/Zend/zend.c:1109
#19 0x2000000801bedc90 in php_execute_script (primary_file=Cannot access memory at address 0x0
) at /usr/src/debug/php-5.1.3RC1/main/main.c:1719
#20 0x2000000801dc5c50 in php_handler (r=Cannot access memory at address 0x0
) at /usr/src/debug/php-5.1.3RC1/sapi/apache2handler/sapi_apache2.c:584
#21 0x20000008000329b0 in ap_run_handler (r=0x2000000808bf2748) at /usr/src/debug/httpd-2.0.52/server/config.c:156
---Type <return> to continue, or q <return> to quit---
#22 0x2000000800033710 in ap_invoke_handler (r=0x2000000808bf2748) at /usr/src/debug/httpd-2.0.52/server/config.c:368
#23 0x200000080002c2a0 in ap_process_request (r=0x2000000808bf2748)
    at /usr/src/debug/httpd-2.0.52/modules/http/http_request.c:246
#24 0x2000000800020940 in ap_process_http_connection (c=0x2000000808be6808)
    at /usr/src/debug/httpd-2.0.52/modules/http/http_core.c:250
#25 0x200000080004a640 in ap_run_process_connection (c=0x2000000808be6808)
    at /usr/src/debug/httpd-2.0.52/server/connection.c:42
#26 0x200000080002e1c0 in child_main (child_num_arg=146712216)
    at /usr/src/debug/httpd-2.0.52/server/mpm/prefork/prefork.c:609
#27 0x200000080002e540 in make_child (s=0x200000080127b620, slot=0)
    at /usr/src/debug/httpd-2.0.52/server/mpm/prefork/prefork.c:649
#28 0x200000080002e7e0 in startup_children (number_to_start=7)
    at /usr/src/debug/httpd-2.0.52/server/mpm/prefork/prefork.c:721
#29 0x200000080002f5d0 in ap_mpm_run (_pconf=0x0, plog=0x20000008012a2298, s=0x200000080127b620)
    at /usr/src/debug/httpd-2.0.52/server/mpm/prefork/prefork.c:940
#30 0x200000080003e3a0 in main (argc=2, argv=0x60000fffffffb548) at /usr/src/debug/httpd-2.0.52/server/main.c:618

----------------------

last execute line of php library ( result ofxdebug_start_trace )  :

0.0060     327104             -> defined() /www/xxxxxxxxx/external/adodb-4.71/drivers/adodb-informix72.inc.php:20

-------------------------------

From adodb-informix72.inc.php:
............
20: if (!defined('IFX_SCROLL')) define('IFX_SCROLL',1);
21:
22: class ADODB_informix72 extends ADOConnection {
23:        var $databaseType = "informix72";
24:        var $dataProvider = "informix";
...............
----------------------------