Fix the TokenTable iterator implementation

The __iter__ function must perform initialization and return the iterator
object itself. The __next__ function must return the next item or raise
StopIteration when no more elements are available.

This fixes the StopIteration exception being uncaught by the for loop when
the iterator reaches the end of the collection. This could be encountered
when calling smbios-token-ctl --dump-tokens.

src/python/libsmbios_c/smbios_token.py

@@ -125,13 +125,16 @@ def __del__(self):
 
     @traceLog()
     def __iter__(self):
-        cur = ctypes.POINTER(Token)()
-        while 1:
-            cur =DLL.token_table_get_next( self._tableobj, cur )
-            if bool(cur):
-                yield cur.contents
-            else:
-                raise StopIteration
+        self._cur = ctypes.POINTER(Token)()
+        return self
+
+    @traceLog()
+    def __next__(self):
+        self._cur =DLL.token_table_get_next( self._tableobj, self._cur )
+        if bool(self._cur):
+            return self._cur.contents
+        else:
+            raise StopIteration
 
     @traceLog()
     def __getitem__(self, id):