Fixed structs.py when structs contain substructs

The previous state machine would happily pick up random names if the
struct had no name of its own. This was picking up typedefs of random
structs and making things really confusing.

Now the rule is that unnamed structs are not printed. Unnamed structs
are usually implementation details so their size is not really useful.

Also made the parsing state machine for objdump outputs more resilient
to these sort of issues.

Also changed structs.py to also report unions if they have a name.

scripts/code.py

@@ -235,6 +235,10 @@ def collect(obj_paths, *,
         is_func = False
         f_name = None
         f_file = None
+        def append():
+            # ignore non-functions and unnamed files
+            if is_func and f_name:
+                defs[f_name] = files.get(f_file, '?')
         # note objdump-path may contain extra args
         cmd = objdump_path + ['--dwarf=info', path]
         if args.get('verbose'):
@@ -250,15 +254,16 @@ def collect(obj_paths, *,
             m = info_pattern.match(line)
             if m:
                 if m.group('tag'):
-                    if is_func:
-                        defs[f_name] = files.get(f_file, '?')
+                    append()
                     is_func = (m.group('tag') == 'DW_TAG_subprogram')
+                    f_name = None
+                    f_file = None
                 elif m.group('name'):
                     f_name = m.group('name')
                 elif m.group('file'):
                     f_file = int(m.group('file'))
-        if is_func:
-            defs[f_name] = files.get(f_file, '?')
+        # don't forget the last function
+        append()
         proc.wait()
         if proc.returncode != 0:
             if not args.get('verbose'):