Enable `set -e' in more tests (plus some tweakings).

Enable `set -e' in more tests (plus some tweakings).

* tests/mkinstall.test: Enable `errexit' shell flag, and related
changes.  Add a trailing `:' command, if needed.
* tests/mdate2.test: Likewise.
* tests/objc.test: Likewise.
* tests/noinst.test: Likewise.
* tests/outdir.test: Likewise.
* tests/number.test: Likewise.
* tests/pluseq.test: Likewise.
* tests/req.test: Likewise.
* tests/rulepat.test: Likewise.
* tests/specflg6.test: Likewise.
* tests/spell3.test: Likewise.
* tests/parse.test: Likewise, and ...
(configure.in): Use the stub created by ./defs, rather than
writing it from scratch.  Remove useless calls to AC_PROG_RANLIB
and AC_OUTPUT.
* tests/mdate4.test: Likewise.
* tests/mkinstall.test: Likewise, and ...
(configure.in): ... drop useless call to `AC_OUTPUT'.
* tests/output.test: Enable `errexit' shell flag, and related
changes.  Add a trailing `:' command.
(configure.in): Modernize.
* tests/output2.test: Likewise.
* tests/output3.test: Likewise.
* tests/output4.test: Likewise.
* tests/mdate3.test: Enable `errexit' shell flag, and related
changes.  Prefer `$me' over hard-coded test name.
* tests/nodistdir.test: Enable `errexit' shell flag, and related
changes.  Prefer trailing `:' over trailing `Exit 0'.
* tests/nodist.test: Likewise.  Also, prefer cat + here-doc over
echo to create input test files, and do not create useless dummy
C source files.
* tests/nodist2.test: Likewise.
* tests/ppf77.test: Enable `errexit' shell flag, with related
changes.  Add a trailing `:' command.  Do not create useless
dummy source files.
* tests/spelling.test: Enable `errexit' shell flag, with related
changes.  Add a trailing `:' command.  Also, grep Automake error
message.
* tests/specflg3.test: Enable `errexit' shell flag, with related
changes.  Avoid unportable use of `-e' option of fgrep.  Prefer
trailing `:' over trailing `Exit 0'.  Remove extra empty lines,
and cosmetic changes to whitespaces.
* tests/obsolete.test: Enable `errexit' shell flag, with related
changes.  Improve verbosity.  Other miscellanous changes.