Upgrade to GCC 3.4.0.
This also makes the port compile (again) under all 64-bit archs. For
amd64, patch-ad modifies config.guess to match GCC's expectation of
x86_64.
Update to a recent snapshot. Among others, this fixes an issue with
the generation of code that fed up recent versions of gas. The
pseudo-symbol _PC_ is now completely eliminated from the generated
code, and replaced by the location counter `.'.