[GOLD] Relocate::relocate() params

[GOLD] Relocate::relocate() params

Some linker code editing needs to change multiple insns.  In some
cases multiple relocations are involved and it is not sufficient to
make the changes independently as relocations are processed, because
doing so might lead to a partial edit.  So in order to safely edit we
need all the relocations available in relocate().  Also, to emit
edited relocs corresponding to the edited code sequence we need some
way to pass information from relocate() to relocate_relocs(),
particularly if the edit depends on insns.  We can't modify input
relocs in relocate() as they are mmapped PROT_READ, nor it is
particularly clean to write relocs to the output at that stage.  So
add a Relocatable_relocs* field to relinfo to mark edited relocs.

Given that relocate is passed the raw reloc pointer, it makes sense to
remove the rel/rela parameter and r_type too.  However, that means the
mips relocate() needs to know whether SHT_REL or SHT_RELA relocs are
being processed.  So add a rel_type for mips, which also has the
benefit of removing relocate() overloading there.

This patch adds the infrastructure without making use of it.

Note that relinfo->rr will be NULL if not outputting relocations.

	* object.h (struct Relocate_info): Add "rr".
	* reloc.h (Relocatable_relocs::set_strategy): New accessor.
	* reloc.cc (Sized_relobj_file::do_relocate_sections): Init
	relinfo.rr for relocate_section and relocate_relocs.
	* powerpc.cc (relocate): Add rel_type and preloc parameters.
	Delete rela and r_type params, instead recalculate these from
	preloc.
	(relocate_relocs): Delete Relocatable_relocs* param, instead
	use relinfo->rr.
	* aarch64.cc: Likewise.
	* arm.cc: Likewise.
	* i386.cc: Likewise.
	* mips.cc: Likewise.
	* s390.cc: Likewise.
	* sparc.cc: Likewise.
	* target.h: Likewise.
	* tilegx.cc: Likewise.
	* x86_64.cc: Likewise.
	* testsuite/testfile.cc: Likewise.
	* target-reloc.h (relocate_section): Adjust to suit.
	(apply_relocation, relocate_relocs): Likewise.