check for This->clipper before unreferencing in dlls/ddraw/surface.c

[Vincent Fourmond]

(IDirectDrawSurfaceImpl_SetClipper): fixes segfault at HMMIV startup.
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 ChangeLog            |    6 ++++++
 dlls/ddraw/surface.c |    5 +++--
 2 files changed, 9 insertions(+), 2 deletions(-)
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