Use the common.isWindows, common.isFreeBSD and common.isSunOS where
possible.
Add common.isOSX and common.isLinux.
Fix `test-fs-read-file-sync-hostname` as in its current form was not
being run anywhere.
PR-URL: https://github.com/nodejs/node/pull/7845
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>