utils: Remove duplicate set non-blocking functions

Current code had 2 implementations of functions that turned on the
O_NONBLOCK flag on file descriptors, none of which were in lib, to avoid
creating yet another implementation for lib code to use, one of existing
implementations was moved to utils.

Change-Id: I1fd242e8b437e485e45127d083c35957ccecf577
Signed-off-by: Dima Kuznetsov <dkuznets@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/29413
Reviewed-by: Yaniv Bronhaim <ybronhei@redhat.com>
Reviewed-by: Piotr Kliczewski <piotr.kliczewski@gmail.com>
Reviewed-by: Nir Soffer <nsoffer@redhat.com>
Reviewed-by: Saggi Mizrahi <smizrahi@redhat.com>