Here are some notes about adding and using this testsuite.

The testsuite adds a directory containing the just built cygwin1.dll to the PATH
(during the run step) so that it can be found by the Windows loader during
testing.

Because we'll probably run into complaints about using two DLLs, we
run cygrun.exe for each test.  All this does is run the test with
CreateProcess() so that we don't attempt to do the special code for
when a cygwin program calls another cygwin program, as this might be a
"multiple cygwins" problem.

Any test that needs to test command line args or redirection needs to
run such a child program itself, as the testsuite will not do any
arguments or redirection for it.  Same for fork, signals, etc.

The testsuite/winsup.api subdirectory is for testing the API to
cygwin1.dll ONLY.  Create other subdirs under testsuite/ for other
classes of testing.

Tests under winsup.api/ either run successfully and exit(0), exit(77) to
indicate a skipped test, or any other exit status to indicate a failure.

Don't print anything to the screen if you can avoid it (except for failure
reasons, of course).  One .c file per test, no compile options are allowed
(we're testing the api, not the compiler).

Tests whose filename is mentioned in XFAIL_TESTS are expected to fail,
effectively reversing the result of those.

"make check" will only work if you run it *on* an NT machine.
Cross-checking is not supported.

To run selected tests, use e.g:
$ make check TESTS="winsup.api/ltp/umask03 winsup.api/ltp/stat06"