tests: fix spurious failure due to missing sleeps

Fixes automake bug#14528.

* THANKS: Give credit to that bug's original reporter.

* t/remake-configure-dependencies.sh: Add few missing '$sleep'
invocations.  I thought that the sleeps implicit in the configure
invocation were enough, but they were not, actually.  Here is what
can happen:

  1. The config.status script is generated by a configure run.
  2. ./config.status and make are run.
  3. The 'print-version' script is modified.
  4. Since that script is listed in $(CONFIGURE_DEPENDENCIES),
     autoconf is re-run.
  5. On a fast-enough machine, the three steps 2-4 above, even
     combined, might have taken less than a second to run;
  6. If the filesystem doesn't have a sub-second timestamp
     resolution, that means the newly-generated configure has
     the same timestamp of the old config.status;
  7. So, config.status is not re-run, and the Makefiles are
     not updated.
  8. Spurious failure!

So we really need more explicit sleeps.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>
tests: fix spurious failure when 'etags' program is Exuberant Ctags

Fixes automake bug#14517.

* t/tags-pr12372.sh: If the 'etags' program in use supports the
'--langmap' option, use it.  That is required to avoid spurious
failures with Exuberant Ctags (at least version 5.8), which by
default do not generate any tags for file extensions it doesn't
recognize.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>
tests: slightly stricter checks in t/cxx-demo.sh

This is a follow-up to the commit fixing automake bug#14493.

* t/cxx-demo.sh: Also check that the built program returns the
correct (i.e., zero) exit status when run.  And improve comments
a little while at it.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>
NEWS: minor fixlets, re-wording, and better text wrapping

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>
typofix: fix grammaro in comments in t/tags-pr12372.sh

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>
release: stable micro release 1.13.3

* configure.ac (AC_INIT): Bump version number to 1.13.3.
* m4/amversion.m4: Likewise (auto-updated by "make bootstrap").

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>
post-release: micro version bump (1.13.3a)

* configure.ac: Bump version: 1.13.3 -> 1.13.3a
* m4/amversion.m4: Likewise (auto-updated by "make bootstrap").

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>
configure: remove an obsolete TODO comment

* configure.ac: Here.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>