x86: Add elf_x86_compute_jump_table_size

x86: Add elf_x86_compute_jump_table_size

Share elf_x86_compute_jump_table_size in elf32-i386.c and
elf64-x86-64.c.

	* elf32-i386.c (elf_i386_compute_jump_table_size): Removed.
	(elf_i386_allocate_dynrelocs): Replace
	elf_i386_compute_jump_table_size with
	elf_x86_compute_jump_table_size.
	(elf_i386_size_dynamic_sections): Likewise.
	* elf64-x86-64.c (elf_x86_64_compute_jump_table_size): Removed.
	(elf_x86_64_allocate_dynrelocs): Replace
	elf_x86_64_compute_jump_table_size with
	elf_x86_compute_jump_table_size.
	(elf_x86_64_size_dynamic_sections): Likewise.
	* elfxx-x86.c (_bfd_x86_elf_link_hash_table_create): Initialize
	got_entry_size.
	* elfxx-x86.h (elf_x86_link_hash_table): Add got_entry_size.
	(elf_x86_compute_jump_table_size): New.