net: deflake TestPacketConn, increase timeout

Tests sometimes failed with:

ok   mime/internal/quotedprintable      0.606s
ok   mime/multipart                     0.819s
--- FAIL: TestPacketConn (0.10s)
    packetconn_test.go:96: PacketConn.ReadFrom failed: WSARecvFrom udp 127.0.0.1:64156: i/o timeout
FAIL
FAIL    net     3.602s
ok      net/http        4.618s
ok      net/http/cgi    0.576s

Theory: 100 ms is too short. Small timer granularity on Wnidows, or an
allocation in the middle causing a GC sometimes?

In any case, increase it to 500 ms.

Change-Id: I48cc4d600eb168db9f85c0fd05335dd630254c3c
Reviewed-on: https://go-review.googlesource.com/4922Reviewed-by: Alex Brainman <alex.brainman@gmail.com>

src/net/packetconn_test.go

@@ -74,9 +74,9 @@ func TestPacketConn(t *testing.T) {
 		}
 		defer closer(c1, netstr[0], tt.addr1, tt.addr2)
 		c1.LocalAddr()
-		c1.SetDeadline(time.Now().Add(100 * time.Millisecond))
-		c1.SetReadDeadline(time.Now().Add(100 * time.Millisecond))
-		c1.SetWriteDeadline(time.Now().Add(100 * time.Millisecond))
+		c1.SetDeadline(time.Now().Add(500 * time.Millisecond))
+		c1.SetReadDeadline(time.Now().Add(500 * time.Millisecond))
+		c1.SetWriteDeadline(time.Now().Add(500 * time.Millisecond))
 
 		c2, err := ListenPacket(tt.net, tt.addr2)
 		if err != nil {
@@ -84,14 +84,14 @@ func TestPacketConn(t *testing.T) {
 		}
 		defer closer(c2, netstr[0], tt.addr1, tt.addr2)
 		c2.LocalAddr()
-		c2.SetDeadline(time.Now().Add(100 * time.Millisecond))
-		c2.SetReadDeadline(time.Now().Add(100 * time.Millisecond))
-		c2.SetWriteDeadline(time.Now().Add(100 * time.Millisecond))
+		c2.SetDeadline(time.Now().Add(500 * time.Millisecond))
+		c2.SetReadDeadline(time.Now().Add(500 * time.Millisecond))
+		c2.SetWriteDeadline(time.Now().Add(500 * time.Millisecond))
+		rb2 := make([]byte, 128)
 
 		if _, err := c1.WriteTo(wb, c2.LocalAddr()); err != nil {
 			t.Fatalf("PacketConn.WriteTo failed: %v", err)
 		}
-		rb2 := make([]byte, 128)
 		if _, _, err := c2.ReadFrom(rb2); err != nil {
 			t.Fatalf("PacketConn.ReadFrom failed: %v", err)
 		}
@@ -130,9 +130,9 @@ func TestConnAndPacketConn(t *testing.T) {
 		}
 		defer closer(c1, netstr[0], tt.addr1, tt.addr2)
 		c1.LocalAddr()
-		c1.SetDeadline(time.Now().Add(100 * time.Millisecond))
-		c1.SetReadDeadline(time.Now().Add(100 * time.Millisecond))
-		c1.SetWriteDeadline(time.Now().Add(100 * time.Millisecond))
+		c1.SetDeadline(time.Now().Add(500 * time.Millisecond))
+		c1.SetReadDeadline(time.Now().Add(500 * time.Millisecond))
+		c1.SetWriteDeadline(time.Now().Add(500 * time.Millisecond))
 
 		c2, err := Dial(tt.net, c1.LocalAddr().String())
 		if err != nil {
@@ -141,9 +141,9 @@ func TestConnAndPacketConn(t *testing.T) {
 		defer c2.Close()
 		c2.LocalAddr()
 		c2.RemoteAddr()
-		c2.SetDeadline(time.Now().Add(100 * time.Millisecond))
-		c2.SetReadDeadline(time.Now().Add(100 * time.Millisecond))
-		c2.SetWriteDeadline(time.Now().Add(100 * time.Millisecond))
+		c2.SetDeadline(time.Now().Add(500 * time.Millisecond))
+		c2.SetReadDeadline(time.Now().Add(500 * time.Millisecond))
+		c2.SetWriteDeadline(time.Now().Add(500 * time.Millisecond))
 
 		if _, err := c2.Write(wb); err != nil {
 			t.Fatalf("Conn.Write failed: %v", err)