Unix: Handle permissions settings for flock-based mutexes in

Unix: Handle permissions settings for flock-based mutexes in
unixd_set_global|proc_mutex_perms().  Allow the functions to be
called for any type of mutex.

This resolves a fatal problem with mod_rewrite on systems where
APR uses flock-based mutex.

It simplifies mod_ssl as well, which had special logic to perform
the chown().  It fixed an init error with mod_ssl on systems where
flock is used when the user had no SSLMutex directive.

The Unix MPMs continue to call unixd_set_global|proc_mutex_perms()
only for SysV sems.  There is no permission problem with flock-based
accept mutexes since the child init logic for the MPMs is done
prior to switching identity.

PR:              20312

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@100189 13f79535-47bb-0310-9956-ffa450edef68