Fix build on Fedora 21.

An open(2) call had two arguments instead of the required three.

Fixes #183.

Submitted by @ssahani.

(cherry picked from commit c5e1205e4906173d74574e30b4ea1c0e182883de)
Signed-off-by: Bruce A. Mah <bmah@es.net>

Conflicts:
	src/iperf_api.c