PR26348, Malloc error in write_zeros

PR26348, Malloc error in write_zeros

This adds a few more sanity checks on ELF objects, and a BFD flag to
disable objcopy and strip when fuzzed input files belong in the "too
hard" basket.

bfd/
	PR 26348
	* bfd.c (struct bfd): Add read_only.
	* elfcode.h (elf_swap_shdr_in): Test both sh_offset and sh_size.
	Set read_only on warning.
	(elf_object_p): Sanity check program header alignment.  Set
	read_only on warning.
	* bfd-in2.h: Regenerate.
binutils/
	PR 26348
	* objcopy.c (copy_object): Report file name with endian error.
	Error and return on abfd->read_only.