Introduce a new test keyword `recursive' for tests that create a

Introduce a new test keyword `recursive' for tests that create a
modified `libtool' script and run the suite on this script.  All
tests with the keyword `libtool' are (by definition) suitable to
be used here.

* tests/cmdline_wrap.at: New test.
* Makefile.am: Adjust.
* tests/testsuite.at (LT_ESCAPE): New macro: clone of Autoconf
AS_ESCAPE that does not escape `$'.
(LT_AT_CHECK): New macro: print a command-to-be-run while
expanding parameters but nothing else.
* tests/stresstest.at: Use LT_AT_CHECK.  Create some files to
expose erroneous globbing errors with `-export-symbols-regex',
similar to those reported by Charles Wilson.  Use `eval' and
adjusted quoting so the expansion doesn't already happen in the
testsuite commands.
* HACKING: Update.