constify elfNN_bed

elfNN_bed was made writable as an expedient means of communicating
ld -z max-page-size and ld -z common-page-size values to BFD linker
code, and even for objcopy to communicate segment alignment between
copy_private_bfd_data, rewrite_elf_program_header and
assign_file_positions_for_load_sections.  Some time later elfNN_bed
elf_osabi was written by gas.  It turns out none of these
modifications to elfNN_bed was necessary, so make it const again.

include/
	* bfdlink.h (struct bfd_link_info): Add maxpagesize and
	commonpagesize.
bfd/
	* elfxx-target.h (elfNN_bed): Constify.
	* bfd.c (bfd_elf_set_pagesize): Delete.
	(bfd_emul_set_maxpagesize, bfd_emul_set_commonpagesize): Delete.
	* elf.c (get_program_header_size): Get commonpagesize from
	link info.
	(_bfd_elf_map_sections_to_segments): Get maxpagesize from link info.
	(assign_file_positions_for_load_sections): Likewise.
	(assign_file_positions_for_non_load_sections): Likewise.
	(rewrite_elf_program_header): Add maxpagesize param.  Set map_p_align.
	(copy_private_bfd_data): Don't call bfd_elf_set_maxpagesize.
	Instead pass maxpagesize to rewrite_elf_program_header.
	* elf32-nds32.c (relax_range_measurement): Add link_info param.
	Get maxpagesize from link_info.  Adjust caller.
	* bfd-in2.h: Regenerate.
gas/
	* config/obj-elf.c (obj_elf_section): Don't set elf_osabi here.
	(obj_elf_type): Likewise.
ld/
	* ld.h (ld_config_type): Delete maxpagesize and commonpagesize.
	* emultempl/elf.em: Use link_info rather than config
	for maxpagesize and commonpagesize.
	* emultempl/ppc32elf.em: Likewise.
	* ldexp.c (fold_binary, fold_name): Likewise.
	* ldemul.c (after_parse_default): Likewise.
	(set_output_arch_default): Don't call bfd_emul_set_maxpagesize
	or bfd_emul_set_commonpagesize.

ld/ld.h

@@ -294,12 +294,6 @@ typedef struct
   /* The size of the hash table to use.  */
   unsigned long hash_table_size;
 
-  /* The maximum page size for ELF.  */
-  bfd_vma maxpagesize;
-
-  /* The common page size for ELF.  */
-  bfd_vma commonpagesize;
-
   /* If set, print discarded sections in map file output.  */
   bfd_boolean print_map_discarded;