freeze exception for gcc-4.5 (i386, amd64 only)

[Matthias Klose <doko@debian.org>]

These packages were prepared before the announcement of the freeze, but not 
uploaded by request of the release team.

gcc-4.5 should be released with squeeze, at least on amd64 and i386. gcc-4.5.1 
was released a week ago, the first bug and regression fix release after the 
initial gcc-4.5.0 release.

 - gcc-4.5 will be an optional compiler, not replacing the current
   defaults.
 - the new version provides the plugin infrastructure, allowing the
   build of the dragonegg and dehydra plugins (the backport of the
   plugin support to 4.4 wasn't sucessful, and the gcc-4.4-plugin-dev
   package was removed again from unstable).  dragonegg and dehydra
   should get a freeze exception too.
 - gcc-4.5 provides LTO (link time optimization) as a major new
   optimization feature.
 - the upload will build several runtime libraries from the 4.5
   sources.  Regression tests did pass for the runtime libs built
   from the 4.5 sources and for 4.4 using the runtime libs from
   4.5.
 - I didn't see bug reports from people using gcc-4.5 from
   experimental, which already run such kind of setup, and from
   Ubuntu users running the current maeverick development release.

If port maintainers do want to enable gcc-4.5 on a port, they should make sure 
that no regressions are introduced by building the runtime libraries from
4.5 and ensure that possible regressions are fixed.

Architectures like mips/mipsel might benefit from this to fix build failures for 
some packages. Backport attempts for #519006 were not sucessful in the past.

  Matthias