ld: Limit cache size and add --max-cache-size=SIZE

ld: Limit cache size and add --max-cache-size=SIZE

When link_info.keep_memory is true, linker caches the relocation
information and symbol tables of input files in memory.  When there
are many input files with many relocations, we may run out of memory.
Add --max-cache-size=SIZE to set the maximum cache size.

bfd/

	PR ld/18028
	* bfd.c (bfd): Add alloc_size.
	* elf-bfd.h (_bfd_elf_link_info_read_relocs): New.
	* elf32-i386.c (elf_i386_check_relocs): Use _bfd_link_keep_memory.
	Update cache_size.
	* elf64-x86-64.c (elf_x86_64_check_relocs): Likewise.
	* elflink.c (_bfd_elf_link_read_relocs): Renamed to ...
	(_bfd_elf_link_info_read_relocs): This.  Update cache_size.
	(_bfd_elf_link_read_relocs): New.
	(_bfd_elf_link_check_relocs): Call _bfd_elf_link_info_read_relocs
	instead of _bfd_elf_link_read_relocs.
	(elf_link_add_object_symbols): Likewise.
	(elf_link_input_bfd): Likewise.
	(init_reloc_cookie_rels): Likewise.
	(init_reloc_cookie): Update cache_size.  Call
	_bfd_elf_link_info_read_relocs instead of
	_bfd_elf_link_read_relocs.
	(link_info_ok): New.
	(elf_gc_smash_unused_vtentry_relocs): Updated.  Call
	_bfd_elf_link_info_read_relocs instead of
	_bfd_elf_link_read_relocs.
	(bfd_elf_gc_sections): Use link_info_ok.  Pass &link_info_ok
	to elf_gc_smash_unused_vtentry_relocs.
	* libbfd-in.h (_bfd_link_keep_memory): New.
	* linker.c (_bfd_link_keep_memory): New.
	* opncls.c (bfd_alloc): Update alloc_size.
	* bfd-in2.h: Regenerated.
	* libbfd.h: Likewise.

include/

	PR ld/18028
	* bfdlink.h (bfd_link_info): Add cache_size and max_cache_size.

ld/

	PR ld/18028
	* NEWS: Mention --max-cache-size=SIZE.
	* ld.texi: Document --max-cache-size=SIZE.
	* ldlex.h (option_values): Add OPTION_MAX_CACHE_SIZE.
	* ldmain.c: (main): Set link_info.max_cache_size to -1.
	* lexsup.c (ld_options): Add --max-cache-size=SIZE.
	(parse_args): Support OPTION_MAX_CACHE_SIZE.
	* testsuite/ld-bootstrap/bootstrap.exp: Add test for
	--max-cache-size=-1.