provided in the gcc_syslibs_devel build feature for building Haiku.
* Simplify declaration of c++ and gcc headers for the legacy compiler -
in the end we always use the ones living by our source tree anyway.
* Fix a couple of missing local declarations for jam variables, which
were necessary to avoid a build problem with strace. There are
probably more bugs like these hiding in our build system files, but
I'm saving the fix for those to the next commit.
* Add new gcc packages to the HaikuPorts (x86*-)repositories.
afde44733f