net: move init function into net.go

It's a single, package-wide init function specified for the net package.

Change-Id: Id5894d65e1a92297cc16803cc5e4d4eef0b4b099
Reviewed-on: https://go-review.googlesource.com/8391Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/net/ipsock.go

@@ -26,12 +26,6 @@ var (
 	supportsIPv4map bool
 )
 
-func init() {
-	sysInit()
-	supportsIPv4 = probeIPv4Stack()
-	supportsIPv6, supportsIPv4map = probeIPv6Stack()
-}
-
 // A netaddr represents a network endpoint address or a list of
 // network endpoint addresses.
 type netaddr interface {

src/net/net.go

@@ -46,6 +46,12 @@ import (
 	"time"
 )
 
+func init() {
+	sysInit()
+	supportsIPv4 = probeIPv4Stack()
+	supportsIPv6, supportsIPv4map = probeIPv6Stack()
+}
+
 // Addr represents a network end point address.
 type Addr interface {
 	Network() string // name of the network