iperf3: update to version 3.1.4

"This release fixes a few minor bugs, including a
(non-security-impacting) buffer overflow fix ported
from upstream cjson."
<http://software.es.net/iperf/news.html#iperf-3-1-4-released>

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>

package/network/utils/iperf3/Makefile

@@ -8,12 +8,12 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=iperf
-PKG_VERSION:=3.1.3
+PKG_VERSION:=3.1.4
 PKG_RELEASE:=1
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=http://downloads.es.net/pub/iperf
-PKG_MD5SUM:=3fb849c24a2370af60687cf673b67bc7
+PKG_MD5SUM:=db61d70ac62003ebe0bf15496bd8c4b3c4b728578a44d0a1a88fcf8afc0e8f76
 
 PKG_MAINTAINER:=Felix Fietkau <nbd@nbd.name>
 PKG_LICENSE:=BSD-3-Clause