Abort glyph rendering if everything is clipped

[Warren_Baird at cimmetry.com]

> It would be better IMO to do that as part of the clip rectangle
> calculation a few lines below.

Well, it was intended as an optimization - if we move the check down to the "if
(flags & (ETO_CLIPPED) ..." clause, we may end up doing a HeapAlloc, and calls
to GetGlyphIndices and GetObject that we don't need to do.  I'd much rather bail
out as soon as we can and avoid doing all of that extra work...

Warren