misc/ios: clean up debugger instance on failure

Also replace repeated `or` clauses with the Python idiomatic list
operator `in`.

Change-Id: I4b178f93eb92996d8b5449ee5d252543624aed9e
Reviewed-on: https://go-review.googlesource.com/111215
Run-TryBot: Elias Naur <elias.naur@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

misc/ios/go_darwin_arm_exec.go

@@ -682,12 +682,14 @@ while True:
 			break
 		sys.stderr.write(out)
 	state = process.GetStateFromEvent(event)
-	if state == lldb.eStateCrashed or state == lldb.eStateDetached or state == lldb.eStateUnloaded or state == lldb.eStateExited:
+	if state in [lldb.eStateCrashed, lldb.eStateDetached, lldb.eStateUnloaded, lldb.eStateExited]:
 		break
 	elif state == lldb.eStateConnected:
 		process.RemoteLaunch(args, env, None, None, None, None, 0, False, err)
 		if not err.Success():
 			sys.stderr.write("lldb: failed to launch remote process: %s\n" % (err))
+			process.Kill()
+			debugger.Terminate()
 			sys.exit(1)
 		# Process stops once at the beginning. Continue.
 		process.Continue()