PR32260: Improve error handling on string merging

PR32260: Improve error handling on string merging

if the input sections are near the max supported size (4G)
we might fail to enlarge the hash table.  The error handling
for this case didn't quite work.  When this happens we can
gracefully fall back to just not deduplicate this section
(and continue with further mergable sections).  We were mixing
that with the case of not being able to even allocate a small
structure (in which case we can as well error out completely),
this disentables both cases.

	bfd/

	PR ld/32260
	* merge.c (sec_merge_maybe_resize): Check overflow in ultimate
	target type.
	(record_section): Return three-state, use new state when unable
	to enlarge hash table.
	(_bfd_merge_sections): Remove current section from merging
	consideration when hashtable can't be enlarged.