Fix warnings that occured on linux using clang

src/providers/twitch/ircmessagehandler.cpp

@@ -10,8 +10,6 @@
 #include "singletons/resourcemanager.hpp"
 #include "singletons/windowmanager.hpp"
 
-#include <memory>
-
 using namespace chatterino::singletons;
 using namespace chatterino::messages;
 
@@ -19,14 +17,9 @@ namespace chatterino {
 namespace providers {
 namespace twitch {
 
-IrcMessageHandler::IrcMessageHandler(singletons::ResourceManager &_resourceManager)
-    : resourceManager(_resourceManager)
-{
-}
-
 IrcMessageHandler &IrcMessageHandler::getInstance()
 {
-    static IrcMessageHandler instance(singletons::ResourceManager::getInstance());
+    static IrcMessageHandler instance;
     return instance;
 }
 

src/providers/twitch/ircmessagehandler.hpp

@@ -3,19 +3,12 @@
 #include <IrcMessage>
 
 namespace chatterino {
-namespace singletons {
-class ChannelManager;
-class ResourceManager;
-}  // namespace singletons
-
 namespace providers {
 namespace twitch {
 
 class IrcMessageHandler
 {
-    IrcMessageHandler(singletons::ResourceManager &resourceManager);
-
-    singletons::ResourceManager &resourceManager;
+    IrcMessageHandler() = default;
 
 public:
     static IrcMessageHandler &getInstance();