mpm_event,worker}: Really perform_idle_server_maintenance() per bucket.

mpm_event,worker}: Really perform_idle_server_maintenance() per bucket.

mpm_{event,worker}: No need to pass num_buckets to perform_idle_server_maintenance() and server_main_loop().

mpm_worker: the last used scoreboard slot depends on pid != 0 only.

Align max_daemons_limit value on all MPMs.

That's the number of scoreboard slots in use, so it shouldn't be negative.
Fix off by one in OS/2 too.

Submitted by: ylavic <ylavic.dev@gmail.com>

Github: closes #274

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1894291 13f79535-47bb-0310-9956-ffa450edef68