* All packaging architecture dependent variables do now have a
respective suffix and are set up for each configured packaging
architecture, save for the kernel and boot loader variables, which
are still only set up for the primary architecture.
For convenience TARGET_PACKAGING_ARCH, TARGET_ARCH, TARGET_LIBSUPC++,
and TARGET_LIBSTDC++ are set to the respective values for the primary
packaging architecture by default.
* Introduce a set of MultiArch* rules to help with building targets for
multiple packaging architectures. Generally the respective targets are
(additionally) gristed with the packaging architecture. For libraries
the additional grist is usually omitted for the primary architecture
(e.g. libroot.so and <x86>libroot.so for x86_gcc2/x86 hybrid), so that
Jamfiles for targets built only for the primary architecture don't
need to be changed.
* Add multi-arch build support for all targets needed for the stage 1
cross devel package as well as for libbe (untested).
* x86_64 is using the existing *_ia32 boot platforms.
* Special flags are required when compiling the loader to get GCC to compile
32-bit code. This adds a new set of rules for compiling boot code rather
than using the kernel rules, which compile using the necessary flags.
* Some x86_64 private headers have been stubbed by #include'ing the x86
versions. These will be replaced later.
