test: disable fs watch tests for AIX

test: disable fs watch tests for AIX

fs watch currently needs special configuration on AIX and we
want to improve under https://github.com/nodejs/node/issues/5085.
Tests are disabled so CI can be green and we can spot other
regressions until this work is complete.

test-async-wrap-check-providers does not aim to test fs watch
but part of the test uses it so that part has been skipped for
AIX

PR-URL: https://github.com/nodejs/node/pull/5187
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>