Merge branch 'maint' into parallel-tests-maint

* maint:
  news: update w.r.t. introduction of AM_DISTCHECK_CONFIGURE_FLAGS
  tests: optimize tests on primary/prefix mismatch for speed
  Warnings about primary/prefix mismatch fixed and extended.
  maintcheck: DISTCHECK_CONFIGURE_FLAGS can be defined on make cmdline
  distcheck: add support for AM_DISTCHECK_CONFIGURE_FLAGS
  docs: better documentation for silent make rules

diff --cc ChangeLog
Simple merge

diff --cc doc/automake.texi
Simple merge

diff --cc tests/Makefile.am
Simple merge

diff --cc tests/Makefile.in
Simple merge