adb: bail out if wait_for_device fails in send_shell_command.

Bug: http://b/27166186
Change-Id: Ib7e9d7e6b909d67a3af94c3517a6a0b54cf17db7
(cherry picked from commit f56c39194f1c2a4f0ea5d2ac20aebf80de4b0ae7)
1 file changed