Fix invalid memory accesses for more corrupt binary files.

Fix invalid memory accesses for more corrupt binary files.

	PR binutils/17531
	* binutils/readelf.c (dynamic_nent): Change type to size_t.
	(slurp_rela_relocs): Use size_t type for nrelas.
	(slurp_rel_relocs): Likewise.
	(get_program_headers): Improve out of memory error message.
	(get_32bit_section_headers): Likewise.
	(get_32bit_section_headers): Likewise.
	(get_64bit_section_headers): Likewise.
	(get_32bit_elf_symbols): Likewise.
	(get_64bit_elf_symbols): Likewise.
	(process_section_groups): Likewise.
	(get_32bit_dynamic_section): Likewise.
	(get_64bit_dynamic_section): Likewise.
	(process_dynamic_section): Likewise.
	(process_version_sections): Likewise.
	(get_symbol_index_type): Likewise.
	(process_mips_specific): Likewise.
	(process_corefile_note_segment): Likewise.
	(process_version_sections): Use size_t type for total.
	(get_dynamic_data): Change type of number parameter to size_t.
	Improve out of memory error messages.
	(process_symbol_table): Change type of nbuckets and nchains to
	size_t.  Skip processing of sections headers if there are none.
	Improve out of memory error messages.