The GNU platform testers reported a number of test errors on
different systems; try to address them.
* tests/thelp.pl: A number of tests timed out with a 4-second
timeout. Increase the default timeout to 10 seconds.
* tests/run_make_tests.pl: Executing directories on cygwin behaves
differently in Perl than make so skip these tests there.
* tests/scripts/options/symlinks: Check for the symlink feature
in make, rather than whether the system supports them.
* tests/scripts/features/implicit_search: On some systems "false"
exits with a different exit code. Use the helper instead.
* tests/scripts/features/loadapi: Ditto.
* tests/scripts/features/output-sync: Sleep before make -f bar in
the first test as well as the second one.
* tests/scripts/features/exec: Skip on cygwin, which seems to
be "UNIX" but where scripts don't run normally.
* tests/scripts/misc/fopen-fail: Skip on cygwin, where make
eventually exits with exit code 0 and no error messages.
Avoid using posix_spawn implementations that fail asynchronously when
the spawned program can't be invoked: this means instead of getting
an error such as "No such file or directory" we get just "Exit 127".
Original implementation of the configure.ac macro provided by
Martin Dorey <martin.dorey@hds.com>
Original implementation of the regression tests provided by
Dmitry Goncharov <dgoncharov@users.sf.net>
* configure.ac: Test whether posix_spawn fails asynchronously. In a
cross-compilation environment, assume that it does not. If we detect
that it does, fall back to fork/exec.
* tests/scripts/features/exec: Add regression tests for different
shebang invocation methods.
