vendor: Fix kcp deadlock

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4461

vendor/github.com/AudriusButkevicius/kcp-go/blacklist.go

@@ -42,7 +42,7 @@ func (m *blacklistMap) has(address string, conv uint32) bool {
 		addr:   address,
 		convID: conv,
 	}]
-	m.mut.Lock()
+	m.mut.Unlock()
 	return ok && t.After(time.Now())
 }
 

vendor/manifest

@@ -21,7 +21,7 @@
 			"importpath": "github.com/AudriusButkevicius/kcp-go",
 			"repository": "https://github.com/AudriusButkevicius/kcp-go",
 			"vcs": "git",
-			"revision": "54928af49abc3a4e5b645f42466a56cebc4a941e",
+			"revision": "8ae5f528469c6ab76110f41eb7a51341b7efb946",
 			"branch": "master",
 			"notests": true
 		},