[Gm2] exception examples

[Gaius Mulley]

Hi,

I've added some exception examples into testsuite/gm2/iso/run/pass.

except2.mod    # ISO Modula-2 exception example code
except.c       # GNU C implementation of the same code
except3.cpp    # C++ implementation of the same code

it looks as if gm2 will follow the C++ mechanics (internally to GCC -
rather than the longjmp/setjmp solution).  As such if there are any
C++ programmers on the list (who have also used ISO M2 exception
handlers) - I'd value you checking the except3.cpp to ensures that it
is semantically the same and that the C++ code is sensible.
It certainly gives the same output as except.c.

regards,
Gaius