Unix: Deleting a duplicating call of a non-blocking mode on descriptor

The call fcntl(fd, F_SETFL, FNDELAY) is superfluous because a flag FNDELAY
duplicates by functionality an existing flag O_NONBLOCK in open() function.
See more info, e.g.: http://linux.die.net/man/2/open

Tested on Gnu/Linux distro's with Qt4 and Qt5.

Change-Id: I01be72e78a9493af8077245cbf6a88e8c9d164ee
Reviewed-by: Laszlo Papp <lpapp@kde.org>
Reviewed-by: Sergey Belyashov <Sergey.Belyashov@gmail.com>