ctf: fix a variety of memory leaks and use-after-free bugs

ctf: fix a variety of memory leaks and use-after-free bugs

These fall into two classes, but are sufficiently intertwined that it's
easier to commit them in one go.

The first is outright leaks, which exceed 1GiB on a normal run, varying
from the tiny (failure to free getline()'s line), through the disastrous
(failure to free items filtered from a list by list_filter(), leading to
the leaking of nearly the whole of the named_structs state, which is
huge).  We also leak the structs_seen hash due to recreating it on
alias_fixup file switch without bothering to destroy it first,

The second is lifetime problems, centred around the stuff allocated and
freed in the detect_duplicates_tu_{init,/done}() functions.  These were
comparing the module name against a saved copy to see if a new vars_seen
needed to be allocated, or whether this was just a flip of TU without a
change of object file and we could get away with just flushing its
contents out -- but unfortunately the state->module_name is assigned
directly from its parameter, and *that* has a lifetime lasting only
within process_file() -- and a deduplication run, of course, involves
iterating over a great many object files.  So everything works as long as
we're flipping from TU to TU within a single object file, and then we
switch object files and are suddenly strcmp()ing with freed memory.
Discard this faulty optimization entirely, and just flush the vars_seen
hash in tu_done() and both create and destroy it in scan_duplicates(),
right where we create and destroy related stuff too.

Something similar happens with the state->dwfl_file_name due to its
derivation from id_file->file_name: if no duplicates are found, we
list_filter() that id_file straight out of the structs_seen list and
free it, and then on the next call state->dwfl_file_name points to freed
memory.

Signed-off-by: Nick Alcock <nick.alcock@oracle.com>
Acked-by: Kris Van Hees <kris.van.hees@oracle.com>
Acked-by: Tomas Jedlicka <tomas.jedlicka@oracle.com>
Orabug: 26283357