[lmi] Forward declarations, __declspec, and wx

[Greg Chicares]

Right now, 'view_ex.hpp' contains this:

// TODO ?? Here and elsewhere, consider losing 'WXDLLEXPORT' on
// forward declarations, depending on the disposition of
//   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20345
//
class WXDLLIMPEXP_FWD_CORE wxDC;
class WXDLLIMPEXP_FWD_CORE wxIcon;
class WXDLLIMPEXP_FWD_CORE wxMenuBar;

Does the 20080309T1213Z change
  http://cvs.savannah.gnu.org/viewvc/lmi/lmi/view_ex.hpp?r1=1.10&r2=1.11
render that comment obsolete so that I can remove it?

IIRC, the disposition of that gcc defect was that it'll be in
MinGW gcc-4.x when that's released someday, but 4.x is still
only a "technology preview" and I don't expect that to change
anytime soon, because there remain serious issues like throwing
exceptions across dll boundaries and building libstdc++ as a dll.