[DotGNU]Compiling Pnet with GCC 3.4.2

[Marcus]

With previous releases in the GCC 3.4 series, I had problem with Pnet when I 
built it with aggressive optimizations. The main problem I ran across was 
that cscc would just bomb out with strange error messages. Since GCC 3.4.2 
was released recently, I tried building Pnet with -O3 (and some other flags), 
and everything works so far.

Some other people reported problems with GCC 3.4.X optimization and Pnet. I 
believe it was on non-X86 platforms. It's possible that the problems are 
fixed on those, too.