elf-attrs.c memory allocation fail

elf-attrs.c memory allocation fail

Report errors rather than segfaulting.

bfd/
	* elf-attrs.c (elf_new_obj_attr): Return NULL on bfd_alloc fail.
	(bfd_elf_add_obj_attr_int): Handle NULL return from the above,
	and propagate return to callers.
	(elf_add_obj_attr_string, elf_add_obj_attr_int_string): Likewise.
	(bfd_elf_add_obj_attr_string): Similarly.
	(_bfd_elf_copy_obj_attributes): Report error on alloc fails.
	(_bfd_elf_parse_attributes): Likewise.
	* elf-bfd.h (bfd_elf_add_obj_attr_int): Update prototype.
	(bfd_elf_add_obj_attr_string): Likewise.
	(bfd_elf_add_obj_attr_int_string): Likewise.
gas/
	* config/obj-elf.c (obj_elf_vendor_attribute): Report fatal
	error on out of memory from bfd attribute functions.
	* config/tc-arc.c (arc_set_attribute_int): Likewise.
	(arc_set_attribute_string, arc_set_public_attributes): Likewise.
	* config/tc-arm.c (aeabi_set_attribute_int): Likewise.
	(aeabi_set_attribute_string): Likewise.
	* config/tc-mips.c (mips_md_finish): Likewise.
	* config/tc-msp430.c (msp430_md_finish): Likewise.
	* config/tc-riscv.c (riscv_write_out_attrs): Likewise.
	* config/tc-sparc.c (sparc_md_finish): Likewise.
	* config/tc-tic6x.c (tic6x_set_attribute_int): Likewise.
	* config/tc-csky.c (md_begin): Likewise.
	(set_csky_attribute): Return ok status.