mpm_common.c implements a handful of config directives; the

mpm_common.c implements a handful of config directives; the
related state has to be re-initialized to the default values
at pre-config time, but that was handled inconsistently by
the MPMs, resulting in unexpected behavior when some of the
directives were removed across restart

move that necessary initialization from the MPMs to common
code run from core's pre-config; MPMs that need to override
defaults can do so by running after core's pre-config (the
NetWare MPM now does that)

the DEFAULT_MAX_REQUESTS_PER_CHILD compile setting wasn't useful
enough to keep

the simple MPM wasn't consistent in which of these directives
were respected and which weren't, and that hasn't changed
(see procmgr.max_requests_per_child vs. ap_max_requests_per_child)

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1086293 13f79535-47bb-0310-9956-ffa450edef68