make sure to not emit immutabilityChanged at startup

if the immutability doesn't actuall change at startup,
don't emit immutabilityChanged even tough each applet needs
one ImmutableConstraint at start to correctly initialize
stuff

Change-Id: Id1fd40ffd62c09a2b092d13d7fb4c556cfb34994

src/plasma/applet.cpp

@@ -521,7 +521,12 @@ void Applet::flushPendingConstraintsEvents()
             action->setEnabled(canConfig);
         }
 
-        emit immutabilityChanged(immutability());
+        //an immutable constraint will alwasy happen at startup
+        //make sure don't emit a change signal for nothing
+        if (d->oldImmutability != immutability()) {
+            emit immutabilityChanged(immutability());
+        }
+        d->oldImmutability = immutability();
     }
 
     // now take care of constraints in special subclass: Contaiment

src/plasma/private/applet_p.cpp

@@ -53,6 +53,7 @@ AppletPrivate::AppletPrivate(KService::Ptr service, const KPluginInfo *info, int
     : appletId(uniqueID),
       q(applet),
       immutability(Types::Mutable),
+      oldImmutability(Types::Mutable),
       appletDescription(info ? *info : KPluginInfo(service)),
       icon(appletDescription.isValid() ? appletDescription.icon() : QString()),
       mainConfig(0),

src/plasma/private/applet_p.h

@@ -81,6 +81,7 @@ public:
 
     // applet attributes
     Types::ImmutabilityType immutability;
+    Types::ImmutabilityType oldImmutability;
     QString launchErrorMessage;
 
     // applet info we keep around in case its needed