[plt-scheme] mzc and C++ and Cygwin

After trying hard, I now see that it is not easy, to use mzc for extending 
mzscheme with a C++ file. It seems to be virtually impossible at the moment.

The problem is that on Cygwin you have to use g++ for linking and mzc does not 
(and it does not use gcc either, but calls ld directly.

It is a pity but I cannot change it. Probably, there are very few people who 
want to use Plt-scheme this way and it would not pay to change this.

-- 
Janos Blazi