various: add more missing apostrophes in comments

Updates #cleanup

Change-Id: I79a0fda9783064a226ee9bcee2c1148212f6df7b
Signed-off-by: Alex Chan <alexc@tailscale.com>

wgengine/magicsock/magicsock_test.go

@@ -2462,7 +2462,7 @@ func TestIsWireGuardOnlyPickEndpointByPing(t *testing.T) {
 			if len(state.recentPongs) != 1 {
 				t.Errorf("IPv4 address did not have a recentPong entry: got %v, want %v", len(state.recentPongs), 1)
 			}
-			// Set the latency extremely high so we dont choose endpoint during the next
+			// Set the latency extremely high so we don't choose endpoint during the next
 			// addrForSendLocked call.
 			state.recentPongs[state.recentPong].latency = time.Second
 		}

wgengine/router/osrouter/router_linux.go

@@ -1617,7 +1617,7 @@ func checkOpenWRTUsingMWAN3() (bool, error) {
 		// We want to match on a rule like this:
 		//    2001:	from all fwmark 0x100/0x3f00 lookup 1
 		//
-		// We dont match on the mask because it can vary, or the
+		// We don't match on the mask because it can vary, or the
 		// table because I'm not sure if it can vary.
 		if r.Priority >= 2001 && r.Priority <= 2004 && r.Mark != 0 {
 			return true, nil