include: Make guiddef.h defines match PSDK.

Protect LPGUID typedef by __LPGUID_DEFINED__ being defined.

Protect LPCLSID and LPFMTID typedefs, IsEqualGUID, IsEqualIID,
IsEqualCLSID, IID_NULL, CLSID_NULL and FMTID_NULL defines by
__IID_DEFINED__ being defined.
1 file changed