Use QHostInfo to get local host name.

Added dependency on QtNetwork for Qt4, too. In Qt5 we depend through
QtQuick.

CMakeLists.txt

@@ -33,6 +33,7 @@ if (USE_QT5)
   qt5_use_modules(sddm Widgets Quick)
 else()
   find_package(Qt4 REQUIRED)
+  set(QT_USE_QTNETWORK TRUE)
   set(QT_USE_QTDECLARATIVE TRUE)
   include(${QT_USE_FILE})
 

src/SessionManager.cpp

@@ -25,11 +25,10 @@
 #include <QCoreApplication>
 #include <QDir>
 #include <QFile>
+#include <QHostInfo>
 #include <QProcess>
 #include <QTextStream>
 
-#include <unistd.h>
-
 using namespace SDE;
 namespace SDE {
     class SessionInfo {
@@ -87,9 +86,7 @@ namespace SDE {
                 d->lastSessionIndex = i;
         }
         // get hostname
-        char hostName[100];
-        gethostname(hostName, 100);
-        d->hostName = hostName;
+        d->hostName = QHostInfo::localHostName();
     }
 
     SessionManager::~SessionManager() {