Merge r1856560, r1856561, r1856846 from trunk:

Merge r1856560, r1856561, r1856846 from trunk:

Update apr_common.m4 to latest (trunk).

Note: why is that file in the httpd repo??

Revert r1856560: was not the latest apr_common.m4 version anyway...

How does that change came in my local workspace in the first place??

Well, our build with latest APR trunk seems to insist on updating apr_common.m4

So be it.

Submitted by: ylavic
Reviewed by: rjung, jorton, jim

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1864614 13f79535-47bb-0310-9956-ffa450edef68