net/iperf3 : Update to 3.9

Index: Makefile
===================================================================
RCS file: /cvs/ports/net/iperf3/Makefile,v
retrieving revision 1.6
diff -u -p -r1.6 Makefile
--- Makefile 21 Jul 2020 02:04:23 -0000 1.6
+++ Makefile 27 May 2021 01:08:31 -0000
@@ -2,7 +2,7 @@

COMMENT= tool to measure maximum achievable bandwidth on IP networks

-V= 3.8.1
+V= 3.9
PKGNAME= iperf3-${V}
DISTNAME= iperf-${V}

Index: distinfo
===================================================================
RCS file: /cvs/ports/net/iperf3/distinfo,v
retrieving revision 1.4
diff -u -p -r1.4 distinfo
--- distinfo 21 Jul 2020 02:04:23 -0000 1.4
+++ distinfo 27 May 2021 01:08:31 -0000
@@ -1,2 +1,2 @@
-SHA256 (iperf-3.8.1.tar.gz) = 5bCA8yc6inFaQQDxOCasLKMcx7ExWSVjGy7PZJV97ZY=
-SIZE (iperf-3.8.1.tar.gz) = 618098
+SHA256 (iperf-3.9.tar.gz) = JLY6JjgjJfdZ8R1CF3mpN7Y8obwXxEWH0vz+2rYKwDg=
+SIZE (iperf-3.9.tar.gz) = 622459
Hi,

Here is a simple patch for net/iperf3 to update to 3.9,
it build well and pass all tests on amd64-6.9 system.

wen