Default is no-op on every platform except for NetWare which is NO. By default we want to run
child in the current address space, the same as the parent process instead of using separate ones.
Performance and complexity are two main reasons.
This is something specific to the NetWare OS that will not be used by other platforms.
The following link as a brief description of protected address space on NetWare:
>>> Jeff Trawick> 6/15/2004 6:59:07 AM >>
>   + * @param addrspace Should the child start in its own address space?  Default is no.
default is yes everywhere but Netware...

what are the concerns with running child in same address space?  if safer to
run in separate address space, shouldn't that be the default?

>     */
>    APR_DECLARE(apr_status_t) apr_procattr_addrspace_set(apr_procattr_t *attr,
>                                                           apr_int32_t addrspace);