Fix potential buffer overruns when creating DLLs.

	PR 29006
	* pe-dll.c (make_head): Use asprintf to allocate and populate a
	buffer containing the temporary name.
	(make_tail, make_one, make_singleton_name_thunk): Likewise.
	(make_import_fixup_mark, make_import_fixup_entry): Likewise.
	(make_runtime_pseudo_reloc): Likewise.
	(pe_create_runtime_relocator_reference): Likewise.