Add iperf3 package

iPerf3 is a tool for active measurements of the maximum achievable bandwidth on
IP networks.

Tested as working on Samsung Chromebook Plus (ARMv8).

packages/iperf3.rb

+require 'package'
+
+class Iperf3 < Package
+  description 'iPerf3 is a tool for active measurements of the maximum achievable bandwidth on IP networks.'
+  homepage 'https://iperf.fr'
+  version '3.2'
+  source_url 'https://github.com/esnet/iperf/archive/3.2.tar.gz'
+  source_sha256 'cb20d3a33e07a3b45a49a358b044f4998f452ef9d1a8a5cbde476b6ab9e9b526'
+
+  binary_url ({
+  })
+  binary_sha256 ({
+  })
+
+  def self.build
+    system "./configure",
+      "--libdir=#{CREW_LIB_PREFIX}",
+      "--prefix=#{CREW_PREFIX}",
+      "--disable-dependency-tracking",
+      "--disable-maintainer-mode"
+    system 'make'
+  end
+
+  def self.install
+    system 'make', "DESTDIR=#{CREW_DEST_DIR}", 'install'
+  end
+end