Enable building <arch>-linux-uclibc toolchains. Note that, due to config

issues for applications, we also create staging_dir/bin/<arch>-linux-*
symlinks which allows us to configure most apps with target=<arch>-linux.

gcc 3.3.2 libstdc++ now correctly identifies uclibc locale support.
There are still some issues (mainly related to wide char time strings
and wcsftime) to be addressed, but those are on hold until the uClibc
locale internals are reworked once again.

With the new stuff, we can also build gcc 2.95 and STLport again, although
the native gcc build for the target is failing.

Archs supported (some archs not yet tested):
 2.95 - i386, arm, mips*, powerpc.
 3.3.2 - Hopefull all for which uClibc has shared lib support.