New entry point in the transfer vector - bfd_relax_section.
* aout-target.h: add to vector, call generic_relax
* bfd-in.h: add to vector
* bfd.c: add #define for vector
* bout.c: add to vector, call generic_relax
* coffcode.h: add to vector, also now has coff specific relax code
for the relaxable H8/300 relocs. Also clean up abs section cruft.
* elf.c: call generic_relax
* ieee.c: call new vector, clean up some bugs due to the creation
of bfd_abs_section
* libbfd.h: add bfd_generic_relax_section EXFUN
* oasys.c: call generic_relax
* reloc.c: implement generic_relax
* seclet.c: moved much of this into coffcode.h
* srec.c: call generic_relax
* targets.c: define new transfer vector