config: choose whether to use the shell or the C wrapper

Offer a config choice on whether to isntall the script wrapper, or
the compiled C wrapper. Update docs/overview.txt accordingly.

tool wrapper: add initial wrapper coded in C

Add an initial wrapper:
- find the realpath of the tool being called
- add the '.' in front of the tool name
- add the '/lib' dir to the base dir of the tool
- set and export LD_LIBRARY_PATH
- execve the real tool

overview: fix table of content, fix the hacker's way

table of content: add missing entry
the hacker's way: no need to "make install"

README: fix some space alignment

duma: fix downloading by forcing extension to .tar.gz

Downoading a non-existing file from sourceforge gives you a "200 OK"
and an index.html. As we try to retrieve a .tar.bz2 first, and duma
is bundled in a .tar.gz, we won't get appropriate content, so
just force the extension to avoid the problem.

Thanks to Ingmar Schraub <is@eseco.de> for pointing out the issue.

x86_64: is a MMU-aware arch, so select ARCH_USE_MMU

duma: fix version string.

DUMA uses '_' not '.' for major/minor/sub separation.

glibc: fix build error caused by incorrect variable assignment

During the conversion to using bash arrays, the glibc build script
was improperly converted, and contains an incorrect variable
assignment to the config_options array.

Merge the bash_array branch.

For every components where it makes sense, use bash arrays (instead
of a string with space-separated values) to store the options pased
to ./configure.

Allow setting --enable-cxx-flags on gcc ./configure

Some setups require one to pass extra CXX flags at the time of ./configure.
Make it easy.