Compile netdev on dragonfly (#314)

* Compile netdev on dragonfly

* Only run netdev bsd test on bsd

* Update README.md

collector/netdev_bsd_test.go

@@ -0,0 +1,53 @@
+// Copyright 2016 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build !nonetdev
+// +build freebsd dragonfly
+
+package collector
+
+import "testing"
+
+type uintToStringTest struct {
+	in  uint64
+	out string
+}
+
+var uinttostringtests = []uintToStringTest{
+	// Copied base10 values from strconv's tests:
+	{0, "0"},
+	{1, "1"},
+	{12345678, "12345678"},
+	{1<<31 - 1, "2147483647"},
+	{1 << 31, "2147483648"},
+	{1<<31 + 1, "2147483649"},
+	{1<<32 - 1, "4294967295"},
+	{1 << 32, "4294967296"},
+	{1<<32 + 1, "4294967297"},
+	{1 << 50, "1125899906842624"},
+	{1<<63 - 1, "9223372036854775807"},
+
+	// Some values that convert correctly on amd64, but not on i386.
+	{0x1bf0c640a, "7500227594"},
+	{0xbee5df75, "3202735989"},
+}
+
+func TestUintToString(t *testing.T) {
+	for _, test := range uinttostringtests {
+		is := convertFreeBSDCPUTime(test.in)
+		if is != test.out {
+			t.Errorf("convertFreeBSDCPUTime(%v) = %v want %v",
+				test.in, is, test.out)
+		}
+	}
+}