x86: Add _bfd_x86_elf_allocate_dynrelocs

x86: Add _bfd_x86_elf_allocate_dynrelocs

Share _bfd_x86_elf_allocate_dynrelocs in elf32-i386.c and elf64-x86-64.c.

	* elf32-i386.c (elf_i386_allocate_dynrelocs): Removed.
	(elf_i386_allocate_local_dynrelocs): Likewise.
	(elf_i386_size_dynamic_sections): Replace
	elf_i386_allocate_dynrelocs/elf_i386_allocate_local_dynrelocs
	with _bfd_x86_elf_allocate_dynrelocs and
	_bfd_x86_elf_allocate_local_dynrelocs.
	* elf64-x86-64.c (elf_x86_64_allocate_dynrelocs): Removed.
	(elf_x86_64_allocate_local_dynrelocs): Likewise.
	(elf_x86_64_size_dynamic_sections): Replace
	elf_x86_64_allocate_dynrelocs/elf_x86_64_allocate_local_dynrelocs
	with _bfd_x86_elf_allocate_dynrelocs and
	_bfd_x86_elf_allocate_local_dynrelocs.
	* elfxx-x86.c (_bfd_x86_elf_allocate_dynrelocs): New function.
	(_bfd_x86_elf_allocate_local_dynrelocs): Likewise.
	* elfxx-x86.h (_bfd_x86_elf_allocate_dynrelocs): New prototype.
	(_bfd_x86_elf_allocate_local_dynrelocs): Likewise.