doc: Use https URLs where possible

src/qt/bitcoin.cpp

@@ -77,7 +77,7 @@ static void RegisterMetaTypes()
   #ifdef ENABLE_WALLET
     qRegisterMetaType<WalletModel*>();
   #endif
-    // Register typedefs (see http://qt-project.org/doc/qt-5/qmetatype.html#qRegisterMetaType)
+    // Register typedefs (see https://doc.qt.io/qt-5/qmetatype.html#qRegisterMetaType)
     // IMPORTANT: if CAmount is no longer a typedef use the normal variant above (see https://doc.qt.io/qt-5/qmetatype.html#qRegisterMetaType-1)
     qRegisterMetaType<CAmount>("CAmount");
     qRegisterMetaType<size_t>("size_t");

src/qt/guiutil.cpp

@@ -655,7 +655,7 @@ bool SetStartOnSystemStartup(bool fAutoStart)
 #elif defined(Q_OS_LINUX)
 
 // Follow the Desktop Application Autostart Spec:
-// http://standards.freedesktop.org/autostart-spec/autostart-spec-latest.html
+// https://specifications.freedesktop.org/autostart-spec/autostart-spec-latest.html
 
 fs::path static GetAutostartDir()
 {

src/qt/notificator.cpp

@@ -66,7 +66,7 @@ Notificator::~Notificator()
 
 #ifdef USE_DBUS
 
-// Loosely based on http://www.qtcentre.org/archive/index.php/t-25879.html
+// Loosely based on https://www.qtcentre.org/archive/index.php/t-25879.html
 class FreedesktopImage
 {
 public: