PR29653, objcopy/strip: fuzzed small input file induces large output file

PR29653, objcopy/strip: fuzzed small input file induces large output file

_bfd_check_format functions should not print errors or warnings if
they return NULL.  A NULL return means the particular target under
test does not match, so there isn't any reason to make a complaint
about the target.  In fact there isn't a good reason to warn even if
the target matches, except via the _bfd_per_xvec_warn mechanism; Some
other target might be a better match.

This patch tidies pe_bfd_object_p with the above in mind, and
restricts the PE optional header SectionAlignment and FileAlignment
fields somewhat.  I chose to warn on nonsense values rather than
refusing to match.  Refusing to match would be OK too.

	PR 29653
	* peXXigen.c (_bfd_XXi_swap_aouthdr_in): Don't emit error about
	invalid NumberOfRvaAndSizes here.  Limit loop copying data
	directory to IMAGE_NUMBEROF_DIRECTORY_ENTRIES.
	* peicode.h (pe_bfd_object_p): Don't clear and test bfd_error
	around bfd_coff_swap_aouthdr_in.  Warn on invalid SectionAlignment,
	FileAlignment and NumberOfRvaAndSizes.  Don't return NULL on
	invalid NumberOfRvaAndSizes.