Remove now unused mbUserDefinedLayer from SdrLayer

Commit 'Special methods NewStandardLayer and SetStandardLayer
not needed' has removed the last user of mbUserDefinedLayer.

Change-Id: Id4d4fbbfa9b1425225181ea6b0750a4205683902
Reviewed-on: https://gerrit.libreoffice.org/62506
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

include/svx/svdlayer.hxx

@@ -67,7 +67,6 @@ class SVX_DLLPUBLIC SdrLayer
     bool mbPrintableODF; // corresponds to ODF draw:display
     bool mbLockedODF; // corresponds to ODF draw:protected
     SdrModel*  pModel; // For broadcasting
-    bool mbUserDefinedLayer;
     SdrLayerID const nID;
 
     SdrLayer(SdrLayerID nNewID, const OUString& rNewName);

svx/source/svdraw/svdlayer.cxx

@@ -68,7 +68,7 @@ void SdrLayerIDSet::PutValue( const css::uno::Any & rAny )
 }
 
 SdrLayer::SdrLayer(SdrLayerID nNewID, const OUString& rNewName) :
-    maName(rNewName), pModel(nullptr), mbUserDefinedLayer(true), nID(nNewID)
+    maName(rNewName), pModel(nullptr), nID(nNewID)
 {
     // ODF default values
     mbVisibleODF = true;
@@ -82,7 +82,6 @@ void SdrLayer::SetName(const OUString& rNewName)
         return;
 
     maName = rNewName;
-    mbUserDefinedLayer = true;
 
     if (pModel)
     {
@@ -95,7 +94,6 @@ void SdrLayer::SetName(const OUString& rNewName)
 bool SdrLayer::operator==(const SdrLayer& rCmpLayer) const
 {
     return (nID == rCmpLayer.nID
-        && mbUserDefinedLayer == rCmpLayer.mbUserDefinedLayer
         && maName == rCmpLayer.maName);
 }