conf: Remove callback from stream when freeing entries in console hash

When a domain has a active console connection and is destroyed the
callback is called on private data that no longer exist causing a
segfault.

src/conf/virconsole.c

@@ -219,6 +219,9 @@ static void virConsoleHashEntryFree(void *data,
     const char *pty = name;
     virStreamPtr st = data;
 
+    /* remove callback from stream */
+    virFDStreamSetInternalCloseCb(st, NULL, NULL, NULL);
+
     /* free stream reference */
     virStreamFree(st);