integration-cli/docker_cli_logs_test.go: Wait()

To avoid a zombie apocalypse, use cmd.Wait() to properly finish
the processes we spawn by Start().

Found while investigating DockerSuite.TestLogsFollowSlowStdoutConsumer
failure on ARM (see
https://github.com/moby/moby/pull/34550#issuecomment-324937936).

[v2: don't expect no error from Wait() when process is killed]

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

integration-cli/docker_cli_logs_test.go

@@ -239,6 +239,8 @@ func (s *DockerSuite) TestLogsFollowSlowStdoutConsumer(c *check.C) {
 	bytes2, err := ConsumeWithSpeed(stdout, 32*1024, 0, nil)
 	c.Assert(err, checker.IsNil)
 
+	c.Assert(logCmd.Wait(), checker.IsNil)
+
 	actual := bytes1 + bytes2
 	c.Assert(actual, checker.Equals, expected)
 }
@@ -288,6 +290,7 @@ func (s *DockerSuite) TestLogsFollowGoroutinesWithStdout(c *check.C) {
 	c.Assert(<-chErr, checker.IsNil)
 	c.Assert(cmd.Process.Kill(), checker.IsNil)
 	r.Close()
+	cmd.Wait()
 	// NGoroutines is not updated right away, so we need to wait before failing
 	c.Assert(waitForGoroutines(nroutines), checker.IsNil)
 }
@@ -303,6 +306,7 @@ func (s *DockerSuite) TestLogsFollowGoroutinesNoOutput(c *check.C) {
 	c.Assert(cmd.Start(), checker.IsNil)
 	time.Sleep(200 * time.Millisecond)
 	c.Assert(cmd.Process.Kill(), checker.IsNil)
+	cmd.Wait()
 
 	// NGoroutines is not updated right away, so we need to wait before failing
 	c.Assert(waitForGoroutines(nroutines), checker.IsNil)