Merge r1480627, r1482859, r1483190, r1484343, r1500437 from trunk:

Mod_proxy used the global pool w/o mutex. fix.


mod_proxy: Use a global mutex for handling workers.


add in child_init which is needed


Add in logno's


conf->mutex is not used... Also, ensure that pool
use is protected

Submitted by: jim, minfrin, jim, jim, jim
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1501223 13f79535-47bb-0310-9956-ffa450edef68