Change how reprocessing is done

Change how reprocessing is done

Currently gdb keeps a vector of attributes that require reprocessing.
However, now that there is a reprocessing flag in the attribute, we
can remove the vector and instead simply loop over attributes a second
time.  Normally there are not many attributes, so this should be
reasonably cheap.

gdb/ChangeLog
2020-09-29  Tom Tromey  <tom@tromey.com>

	* dwarf2/read.c (skip_one_die): Update.
	(read_full_die_1): Change how reprocessing is done.
	(partial_die_info::read): Update.
	(read_attribute_value): Remove need_reprocess parameter.
	(read_attribute): Likewise.
	* dwarf2/attribute.h (struct attribute) <requires_reprocessing_p>:
	New method.