handle MIPS specific sections.
* libelf.h (elf_backend_data): Pass fourth argument to
elf_backend_section_from_bfd_section to permit it to control the
section index to use.
(elf_obj_tdata): Add gp and gp_size fields.
(elf_gp, elf_gp_size): New accessor macros.
* elfcode.h: Removed a number of unused local variables.
(elf_fake_sections): Clear section header before calling
elf_backend_fake_sections, not after.
(prep_headers): Return true at end.
(elf_section_from_bfd_section): Pass retval argument to
elf_backend_section_from_bfd_section.
* elf32-hppa.c (elf32_hppa_backend_section_from_bfd_section):
Accept and ignore new retval argument.
* bfd.c: Include libelf.h.
(bfd_set_gp_size): Handle ELF targets.
* Makefile.in (bfd.o): Depends upon libelf.h.
(elf32-mips.o): Depends upon $(INCDIR)/elf/mips.h.