Description:
------------
This is more a feature request for PHP.

If you are running apache with vhosts support, you need to set the open_basedir for each vhost for security reasons.

The problem is, you cannot set a global open_basedir setting which is valid all time for any vhost (in the php.ini e.g.)! 
If the open_basdir setting is new set in a httpd.conf vhost-section, the global value will be overwritten. In this case you have to set the "global" setting in the httpd.conf vhost-section again. This is very much administration overhead! And the very most problem is, the httpd.conf vhost sections are often automatically generated (think about PLESK or other webhosting tools).

A new option called something like "global_open_basedir" would be very appreciated for directories like /Tmp-Dir /Path-To-Pear-Installation etc.

Reproduce code:
---------------
*** php.ini ***
; open_basedir, if set, limits all file operations to the defined directory
; and below.  This directive makes most sense if used in a per-directory
; or per-virtualhost web server configuration file. This directive is
; *NOT* affected by whether Safe Mode is turned On or Off.
open_basedir = "/tmp:/usr/share/php5/PEAR"
****************


*** httpd.conf ***
<VirtualHost xx.xx.xx.xx:80>
   [...]
   php_admin_flag engine on
   php_admin_flag safe_mode off
   php_admin_value open_basedir "/srv/www/vhosts/domain1.tld/httpdocs:/tmp:/usr/share/php5/PEAR"
[...]
</VirtualHost>

<VirtualHost xx.xx.xx.xx:80>
   [...]
   php_admin_flag engine on
   php_admin_flag safe_mode off
   php_admin_value open_basedir "/srv/www/vhosts/domain2.tld/httpdocs:/tmp:/usr/share/php5/PEAR"
[...]
</VirtualHost>

[some other 50 vhosts...]
****************

Expected result:
----------------
*** php.ini ***
; open_basedir, if set, limits all file operations to the defined directory
; and below.  This directive makes most sense if used in a per-directory
; or per-virtualhost web server configuration file. This directive is
; *NOT* affected by whether Safe Mode is turned On or Off.
;
;open_basedir =

; valid for any vhost if not overwritten
global_open_basedir = "/tmp:/usr/share/php5/PEAR"
****************


*** httpd.conf ***
<VirtualHost xx.xx.xx.xx:80>
   [...]
   php_admin_flag engine on
   php_admin_flag safe_mode off
   php_admin_value open_basedir "/srv/www/vhosts/domain1.tld/httpdocs"
[...]
</VirtualHost>

<VirtualHost xx.xx.xx.xx:80>
   [...]
   php_admin_flag engine on
   php_admin_flag safe_mode off
   php_admin_value open_basedir "/srv/www/vhosts/domain2.tld/httpdocs"
[...]
</VirtualHost>

[some other 50 vhosts...]
****************

Actual result:
--------------
at the moment you can set the open_basedir configuration in php.ini but you cannot extend it with further directories in the vhost-section part. 
So, you do automatically overwrite the open_basedir setting in the vhost-section part which is not very handy for administrative tasks.
A sepparate global_open_basedir setting would solve the problem and offer more control and less work for system administrators.