Added an inherit flag to apr_socket_create and other socket creation

Added an inherit flag to apr_socket_create and other socket creation
functions.  This allows APR programs to specify that a socket should
be passed to any child processes that are created.  The inherit flag
is only meaningful if programs use apr_process_create().  This
also adds a couple of macros that allow APR types to set and unset
the inherit flag.

This also fixes Apache to use the new API.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@89557 13f79535-47bb-0310-9956-ffa450edef68