[C++-sig] Workaround for fatal error C1204

[David Abrahams]

If you've been getting 

   fatal error C1204:Compiler limit:internal structure overflow

messages with VC6 and/or VC7, you might find they go away after
updating to the latest CVS. I've checked in a workaround for some of
the ways in which this can occur.

-- 
                       David Abrahams
   dave at boost-consulting.com * http://www.boost-consulting.com
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