vclwidget: add some safety net asserts

Change-Id: I5fa19ec6161ab97eb7df8b52a268917f41ae2205
diff --git a/include/vcl/outdev.hxx b/include/vcl/outdev.hxx
index f5875b7..4e2341a 100644
--- a/include/vcl/outdev.hxx
+++ b/include/vcl/outdev.hxx
@@ -274,11 +274,13 @@ private:

    inline void acquire() const
    {
        assert(!mbDisposed);
        mnRefCnt++;
    }

    inline void release() const
    {
        assert(mnRefCnt>0);
        if (!--mnRefCnt)
            delete const_cast<OutputDevice*>(this);
    }
diff --git a/include/vcl/vclptr.hxx b/include/vcl/vclptr.hxx
index 3e0de76..6ab6373 100644
--- a/include/vcl/vclptr.hxx
+++ b/include/vcl/vclptr.hxx
@@ -270,6 +270,7 @@ public:
    ~ScopedVclPtr()
    {
        VclPtr<reference_type>::disposeAndClear();
        assert(VclPtr<reference_type>::get() == nullptr); // make sure there are no lingering references
    }
private:
    // Most likely we don't want this default copy-construtor.