scripts: fix dumping the config for companion libraries for target

Companion libraries can be disable for the host, but still used for
the target (eg. binutils or gdb). Dump the version also in this case.

scripts: fix dumping config

libelf has been moved to being a companion library, now.

config: hide entries when in backend mode

This implies hidding entries for:
- binutils libraries
- dmalloc
- duma
- native gdb
- ltrace
- strace
- sstrip

kconfig: silence a warning about undefined env variable

When using an environment variable to set a config entry,
don'twarn if it is not defined. Update doc accordingly.

config: prepare for build-system backend

When acting as a backend for a build-system, we should not build
any application that runs on the target, that is:
- no native gdb
- no companion libraries
- no binutils libraries
- no debug tools (save for gdbserver)
- ...

Here, we simply prepare the (hidden) config option that will detect
that we are acting as a back-end.

Update doc accordingly.

samples: fix samples

kernel/linux: add latest versions 2.6.32.10 and 2.6.33.1

debug/gdb: fix building the native tic

The native 'tic' will _always_ be run on the build
machine, so no need to handle canadian/native/...

Reported by: Trevor Woerner
http://sourceware.org/ml/crossgcc/2010-03/msg00055.html
(transplanted from 26e89d367ea11660fd3a0bf0bcad8763e4fa21cf)

debug/gdb: fix building the native tic

The native 'tic' will _always_ be run on the build
machine, so no need to handle canadian/native/...

Reported by: Trevor Woerner
http://sourceware.org/ml/crossgcc/2010-03/msg00055.html

scripts: fix the release script to use the C locale

Force use of the C locale to ensure messages are recognised by the script.