tdf#104495: prevent autotext to crash when drag&drop

See bt https://bugs.documentfoundation.org/attachment.cgi?id=129407

For non regression, I retested tdf#91125 since the delete comes from
https://cgit.freedesktop.org/libreoffice/core/commit/?id=06ecf7d2aebe64226142ee27c2512351960f8bb1

Change-Id: I7ce833ffce20f1f159242014ba8ffe0ce5b7b11c
Reviewed-on: https://gerrit.libreoffice.org/31773
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Maxim Monastirsky <momonasmon@gmail.com>
(cherry picked from commit 8776c20c1c72110d0f205150913eb17cdf3f1aaa)
Reviewed-on: https://gerrit.libreoffice.org/31784
Reviewed-by: Michael Meeks <michael.meeks@collabora.com>
diff --git a/svtools/source/contnr/treelistbox.cxx b/svtools/source/contnr/treelistbox.cxx
index 5052c0a..5239e36 100644
--- a/svtools/source/contnr/treelistbox.cxx
+++ b/svtools/source/contnr/treelistbox.cxx
@@ -1178,7 +1178,6 @@ void SvTreeListBox::StartDrag( sal_Int8, const Point& rPosPixel )
    {
        nDragDropMode = nOldDragMode;
        DragFinished( DND_ACTION_NONE );
        delete pContainer;
        return;
    }