unix: remove FSEventStreamFlushSync() call
unix: remove FSEventStreamFlushSync() call

This call, in the context of file watching, appears to trigger
assertion warnings on some macOS configurations.

Refs: https://github.com/nodejs/node/issues/854
Fixes: https://github.com/libuv/libuv/issues/1334
PR-URL: https://github.com/libuv/libuv/pull/1349
Reviewed-By: Fedor Indutny <2e687df1861dff46b1954016c7b2cad32e8742d4@gmail.com>
Reviewed-By: Saúl Ibarra Corretgé <8a7991f6950ea189abf159d6ec98d2fcc13dc5f6@gmail.com>

unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso