We now throw all of the machvecs in to .machvec.init and either
select one on the command line, or copy out the first (and
usually only) one to sh_mv. The rest are freed as usual.

This gets rid of all of the silly sh_mv aliasing and makes the
selection explicit rather than link-order dependent.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>