Merge r1809302, r1809303, r1809305, r1809311, r1809314, r1809713 from trunk:

Merge r1809302, r1809303, r1809305, r1809311, r1809314, r1809713 from trunk:

config: allow to specify flags when registering modules.

First one is AP_MODULE_FLAG_ALWAYS_MERGE.

mod_ssl: follow up to r1809302.

Make use of AP_MODULE_FLAG_ALWAYS_MERGE.

config: follow up to r1809302.
We need to check that the module itself is at the right version.

config: follow up to r1809302.

Provide a convenient function to get module flags, and remove useless
AP_MODULE_HAS_FLAGS checks in the core, core's version is at current MMN.

config: follow up to r1809302.
Associate ap_get_module_flags() to MMN bump.

On the trunk:

mod_ssl: make the new module flag used.

Submitted by: ylavic, icing
Reviewed by: icing, ylavic, covener

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1821071 13f79535-47bb-0310-9956-ffa450edef68