Use "wx" prefix for the GUIDs we (re)define in wxMSW code.

Use "wx" prefix for the GUIDs we (re)define in wxMSW code.

CLSID_AutoComplete became ambiguous with MinGW because it does define it in
its shlguid.h header (although MSVC/Platform SDK does not define this one) so
use a "wx" prefix for it to avoid ambiguity. Also use the same prefix for the
IID_IAutoCompleteDropDown value we define for consistency.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67569 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775