Free linker hash table from bfd_close.

Free linker hash table from bfd_close.

Also tidies numerous error exit paths in various link_hash_table_create
functions that failed to free memory.

include/
	* bfdlink.h (struct bfd_link_hash_table): Add hash_table_free field.
bfd/
	* archive.c: Include bfdlink.h.
	(_bfd_archive_close_and_cleanup): Call linker hash_table_free.
	* bfd.c (struct bfd): Add is_linker_output field.
	* elf-bfd.h (_bfd_elf_link_hash_table_free): Update prototype.
	* linker.c (_bfd_link_hash_table_init): Set up hash_table_free,
	link.hash and is_linker_output.
	(_bfd_generic_link_hash_table_free): Replace bfd_link_hash_table*
	param with bfd*.  Assert is_linker_output and link.hash, and
	clear them before exit.
	* elf-m10300.c (elf32_mn10300_link_hash_table_free): Replace
	bfd_link_hash_table* param with bfd*.  Hack is_linker_output
	and link.hash so we can free two linker hash tables.
	(elf32_mn10300_link_hash_table_create): Create static_hash_table
	first.  Clean up on errors.  Set hash_table_free pointer.
	* elf32-arm.c (elf32_arm_link_hash_table_free): Replace
	bfd_link_hash_table* param with bfd*.
	(elf32_arm_link_hash_table_create): Clean up on errors.  Set
	hash_table_free pointer.
	* elf32-avr.c, * elf32-hppa.c, * elf32-i386.c, * elf32-m68hc1x.c,
	* elf32-m68k.c, * elf32-metag.c, * elf32-nios2.c, * elf32-xgate.c,
	* elf64-ia64-vms.c, * elf64-ppc.c, * elf64-x86-64.c, * elflink.c,
	* elfnn-aarch64.c, * elfnn-ia64.c, * elfxx-sparc.c,
	* xcofflink.c: Similarly.
	* simple.c (bfd_simple_get_relocated_section_contents): Save and
	clear link.next before creating linker hash table.  Clean up on
	errors, and restore link.next on exit.
	* elf32-m68hc1x.h (m68hc11_elf_bfd_link_hash_table_free): Delete.
	* elf32-xgate.h (xgate_elf_bfd_link_hash_table_free): Delete.
	* elfxx-sparc.h (_bfd_sparc_elf_link_hash_table_free): Delete.
	* libcoff-in.h (_bfd_xcoff_bfd_link_hash_table_free): Delete.
	* hash.c (bfd_hash_table_init_n): Free table on error.
	* libbfd-in.h (_bfd_generic_link_hash_table_free): Update proto.
	* bfd-in2.h: Regenerate.
	* libbfd.h: Regenerate.
	* libcoff.h: Regenerate.