Move defines into settings.hxx

For some unknown reason, there are a bunch of defines in the middle of
Desktop::SystemSettingsChanging() that should really be in
include/vcl/settings.hxx. I have now moved DRAG_OPTIONS_ALL into
settings.hxx but entirely removed DRAG_OPTIONS_NONE because it is
confusing. I also removed it in the one place this combination of options
is used in the Desktop class.

I have also removed the options DRAG_OPTIONS_OBJECT_* from settings.hxx
because they are used nowhere in the code. I have carefully looked
through the code and nothing flips bits 0x00000004 or 0x00000008 on
the private member of ImplStyleData's mnDragFullOptions in any way.
Basically, it is safe to remove.

Change-Id: Icf6268f940cfaed271bd43c977473fecfc726949
Signed-off-by: Stephan Bergmann <sbergman@redhat.com>