various: add more missing apostrophes in comments

Updates #cleanup

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

tka/tailchonk.go

@@ -678,7 +678,7 @@ func markAncestorIntersectionAUMs(storage Chonk, verdict map[AUMHash]retainState
 	toScan := make([]AUMHash, 0, len(verdict))
 	for h, v := range verdict {
 		if (v & retainAUMMask) == 0 {
-			continue // not marked for retention, so dont need to consider it
+			continue // not marked for retention, so don't need to consider it
 		}
 		if h == candidateAncestor {
 			continue
@@ -781,7 +781,7 @@ func markDescendantAUMs(storage Chonk, verdict map[AUMHash]retainState) error {
 	toScan := make([]AUMHash, 0, len(verdict))
 	for h, v := range verdict {
 		if v&retainAUMMask == 0 {
-			continue // not marked, so dont need to mark descendants
+			continue // not marked, so don't need to mark descendants
 		}
 		toScan = append(toScan, h)
 	}

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