test: test-fs-watch should be made non-flaky

[joaocgreis]

simple/test-fs-watch is currently marked as flaky on Mac OS. It should be investigated and made non-flaky.

Quick command for testing:

time (OK=0; NOK=0; for i in `seq 10000`; do ./out/Release/node test/simple/test-fs-watch.js && OK=$(($OK+1)) || NOK=$(($NOK+1)); echo "$i   OK: $OK   NOT OK: $NOK"; done)

Links:

• File: https://github.com/joyent/node/blob/b8ac6584faf00f6bc9302913ea58e54dcf8f559c/test/simple/test-fs-watch.js
• File history: https://github.com/joyent/node/commits/b8ac6584faf00f6bc9302913ea58e54dcf8f559c/test/simple/test-fs-watch.js
• Marked flaky on: Mar 10, 2015

/cc @joyent/node-collaborators

[brendanashworth]

This was [somewhat] resolved in io.js: nodejs/node#1275