Fix uninitialized memory and logic error in PaintRedirector

The refactoring of Compositor starting with b1739c3 caused some
regressions due to variables in Workspace and Compositor not
being initialized. Furthermore there was a boolean logic error
in PaintRedirector causing the decorations not to paint.

BUG: 305875

composite.cpp

@@ -87,7 +87,14 @@ Compositor::Compositor(QObject* workspace)
     : QObject(workspace)
     , m_suspended(!options->isUseCompositing())
     , m_blocked(false)
+    , cm_selection(NULL)
+    , vBlankInterval(0)
+    , fpsInterval(0)
     , m_xrrRefreshRate(0)
+    , forceUnredirectCheck(false)
+    , m_finishing(false)
+    , m_timeSinceLastVBlank(0)
+    , m_nextFrameDelay(0)
     , m_scene(NULL)
 {
     connect(&unredirectTimer, SIGNAL(timeout()), SLOT(delayedCheckUnredirect()));

paintredirector.cpp

@@ -82,7 +82,7 @@ bool PaintRedirector::eventFilter(QObject* o, QEvent* e)
         break;
     }
     case QEvent::Paint: {
-        if (Workspace::self()->compositingActive()) {
+        if (!Workspace::self()->compositingActive()) {
             return false;
         }
         if (!recursionCheck) {

workspace.cpp

@@ -105,6 +105,7 @@ Workspace::Workspace(bool restore)
 #ifdef KWIN_BUILD_SCREENEDGES
     , m_screenEdgeOrientation(0)
 #endif
+    , m_compositor(NULL)
     // Unsorted
     , active_popup(NULL)
     , active_popup_client(NULL)
@@ -482,6 +483,7 @@ void Workspace::init()
 Workspace::~Workspace()
 {
     delete m_compositor;
+    m_compositor = NULL;
     blockStackingUpdates(true);
 
     // TODO: grabXServer();