[system,arm-linux] Add ARM Linux target.
[registry,arm-linux] Add ARM Linux to registry.
[arm-linux] Fix configure.ac for cross-compilation.
[arm-linux] Update build system for arm-linux.
[arm-linux] Update jamfiles for arm-linux target.
[doc,hackers] Update reference to $target.
Merge pull request #477 from micrypt/arm-target

[system,arm-linux] Add ARM Linux target.