Fix duplicate symbol link errors in wxMSW wxTextEntry code.

Don't include <initguid.h> too soon, as this affects the headers included
after it instead of just our own uses of DEFINE_GUID() as intended.

This resulted in link errors because of duplicate definitions of the many
standard GUIDs when using MinGW for which we include, for whatever reason,
shlguid.h.

This fixes the change of r67573.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74600 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775