Tidy code setting ASSOCIATED_VECS, which could be fooled by unusual
configure options such as --enable-targets="srec,all".
* targets.c (_bfd_associated_vector): Remove comma after
ASSOCIATED_VECS.
* configure.ac: Set assocvecs from targ_defvec and
targ_selvecs when handling the target, rather than assuming
those variables are still set for the target when handling
--enable-targets=all. Move code making assocvecs unique
later. Do so in a way that need not run sed afterwards, and
leave a trailing comma.
* configure: Regenerate.