Move the actual binutils code to a backend function that builds the
required combo of build/host/target as requested by a frontend.
This split is currently a no-op, but is required for the upcoming
canadian-cross rework, where we'll be needing to build two binutils,
one for build/build/target, and one for build/host/target.
This applies to the three binutils:
- GNU binutils
- elf2flt
- sstrip
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>
sstrip is now alone in its 'tools' menu, and we will probably never gain
any other 'tool'. Besides, sstrip is just strip, but a little bit more
agressive, so it deserves going to the 'binary utilities' menu.