Use delegating constructors in Pty

And move the code from init() to the constructor, and remove init(), not
needed any more.

src/Pty.cpp

@@ -24,19 +24,13 @@
 
 using Konsole::Pty;
 
-Pty::Pty(int masterFd, QObject *aParent)
-    : KPtyProcess(masterFd, aParent)
-{
-    init();
-}
-
 Pty::Pty(QObject *aParent)
-    : KPtyProcess(aParent)
+    : Pty(-1, aParent)
 {
-    init();
 }
 
-void Pty::init()
+Pty::Pty(int masterFd, QObject *aParent)
+    : KPtyProcess(masterFd, aParent)
 {
 #if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
     // Must call parent class child process modifier, as it sets file descriptors ...etc

src/Pty.h

@@ -150,7 +150,8 @@ Q_SIGNALS:
     void receivedData(const char *buffer, int length);
 
 protected:
-// TODO: remove this; in Qt6 use setChildProcessModifier() in init()
+    // TODO: remove this; the method is removed from QProcess in Qt6
+    // instead use setChildProcessModifier() in the constructor
 #if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
     void setupChildProcess() override;
 #endif