ImUtil.h

I noticed that ImUtil.h wasn't actually unused.  The prototypes that
were in it are used in libXext, it's just the lack of prototypes doesn't
get complained about because of the warning levels being too low.  It
seems like the change to remove it from the public API and remove the
include from libXext should be backed out at least until the API is in
fact unused.

-- 
Eric Anholt                                
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http://people.freebsd.org/~anholt/         
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