Merge r1869541, r1869543, r1869564, r1869565, r1869684, r1869697, r1869703, r1869708, r1869729, r1869801, r1869846, r1870047, r1870077, r187…
Merge r1869541, r1869543, r1869564, r1869565, r1869684, r1869697, r1869703, r1869708, r1869729, r1869801, r1869846, r1870047, r1870077, r1870080, r1870086, r1870150, r1870550 from trunk:Run buildconf using the specific APR/APR-util versions if configured.Revert r1869541 and always run httpd's buildconf against the Debian APR,which does include the *.m4 files.Add shared-mpms build, add build against APR trunk (httpd trunk only).Fix handling and ensure safe caching of APR trunk build.Fix yaml typo.* .travis.yml: Build on Bionic by default, only build w/APR 1.5.x for the 2.4.x branch.* .travis.yml, test/travis_run_linux.sh: Pass BUILDCONF to buildconf and add job which uses the new option.Install PCRE v2 (10.x) by default, add a job testing with PCRE "v1" (8.x).Minor Travis doc updates and a todo list. Test IRC and e-mail notifications.Add build job for trunk on Xenial with custom APR/APR-util builds.Try mailing dev@ for Travis build results.The defaults are to mail:- on success (if changed from failure)- on failure (always)Specify make flags globally and work around PR 63942 for regenerationof server/util_expr parser.Support travis builds against APR/APR-util non-trunk branches.Add job for APR 1.7.x + APR-util 1.7.x.Build on s390x (interesting test target since it's big-endian).IRC notifications work, e-mail doesn't; branches are done.ppc64le builds also work but are extremely slow, so not enabled.Doc updates for Travis. Note that APU_VERSION=trunk doesn't work per rpluem's mail. Skip ap_expr regeneration for 2.4.x.