tests: more explicative names for some tests

tests: more explicative names for some tests

Do so for several Texinfo-related tests.  Note that some of such tests
with suboptimal names are *not* renamed; that's because they are going
to be removed in the master branch anyway (since they check from some
soon-to-be-removed features), so renaming them would be wasted work,
and could even create useless merge conflicts.

* t/txinfo2.sh: Rename ...
* t/txinfo-no-extra-dist.sh: ... like this.
* t/txinfo3.sh: Rename ...
* t/txinfo-suffix-less-info.sh: ... like this.
* t/txinfo4.sh: Rename ...
* t/txinfo-unrecognized-info-suffix.sh: ... like this.
* t/txinfo6.sh: Rename ...
* t/txinfo-other-suffixes.sh: ... like this.
* t/txinfo7.sh: Rename ...
* t/txinfo-add-missing.sh: ... like this.
* t/txinfo8.sh: Rename ...
* t/txinfo-add-missing2.sh: ... like this.
* t/txinfo9.sh: Rename ...
* t/txinfo-no-repeated-targets.sh: ... like this.
* t/txinfo17.sh: Rename ...
* t/txinfo-setfilename-repeated.sh: ... like this.
* t/txinfo13.sh: Rename ...
* t/txinfo-subdir-pr343.sh: ... like this.
* t/txinfo16.sh: Rename ...
* t/txinfo-info-in-srcdir.sh: ... like this.
* t/txinfo21.sh: Rename ...
* t/txinfo-many-output-formats.sh: ... like this.
* t/txinfo22.sh: Rename ...
* t/txinfo-override-texinfo-tex.sh: ... like this.
* t/txinfo26.sh: Rename ...
* t/txinfo-absolute-srcdir-pr408.sh: ... like this.
* t/txinfo27.sh: Rename ...
* t/txinfo-no-installinfo.sh: ... like this.
* t/txinfo29.sh: Rename ...
* t/txinfo-override-infodeps.sh: ... like this.
* t/txinfo31.sh: Rename ...
* t/txinfo-setfilename-suffix-match.sh: ... like this.
* t/txinfo32.sh: Rename ...
* t/txinfo-bsd-make-recurs.sh: ... like this.
* t/txinfo33.sh: Rename ...
* t/txinfo-clean.sh: ... like this.
* t/list-of-tests.mk: Adjust.

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