gdb/dwarf: change htabs holding dwo_unit objects to gdb::unordered_set

Change a few occurences of htabs holding `dwo_unit *` values, using
their signature as identity, to gdb::unordered_set.
allocate_dwo_unit_table and allocate_dwp_loaded_cutus_table appeared to
create hash tables with identical behavior, so they both use the same
set type now.

The only expected change in behavior is that when there are multiple
units with the same signature, we will now keep the unit previously in
the set, rather than overwriting it.  But this seems ok, as it's a case
of bad DWARF.

Also, in the complaint in create_debug_type_hash_table, I think we
previously erroneously printed the same sect_off twice.

Change-Id: I57739977735ee1fd5c7b754107f5624f0621baa5
Approved-By: Tom Tromey <tom@tromey.com>

0 files changed, 0 insertions, 0 deletions