[perl #93454] Free deleted iterator when freeing hash

[perl #93454] Free deleted iterator when freeing hash

Commit 7d6175e, which did a fix-up after commit e0171a1a3, which
introduced hfree_next_entry, did not account for the fact that
hfree_next_entry frees the hash iterator before removing and returning
the next value.

It changed the callers to check the number of keys to determine
whether anything else needed to be freed, which meant that
hfree_next_entry was called one time less than necessary on hashes
whose current iterator had been deleted and which consequently
appeared empty.

This fixes that.

I don’t know how to test it, but the string table warnings were caus-
ing test failures on VMS, so maybe that’s good enough.