gdbus: Avoid reporting GDBusClient disconnect twice

No matter if disconnection was reported previously, g_dbus_client_unref()
was always calling service disconnect callback. This patch fix the
following scenario:
1) service disconnects from the bus
2) disconnect callback gets called
3) client calls g_dbus_client_unref(), disconnect callback is called
   again.
gdbus: Fix use after free

Refactor filter_data_remove_callback so that we do not iterate over
freed pointer.
gdbus: Fix crash when calling g_dbus_add_service_watch

If g_dbus_add_service_watch is called for service which bus name is
already known the following crash can happen:

invalid read of size 1
  at 0x4C2A2F2: strlen (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
  by 0x4E97722: g_strdup (in /usr/lib64/libglib-2.0.so.0.3800.2)
  by 0x405B0C: update_name_cache (watch.c:435)
  by 0x405C37: update_service (watch.c:593)
  by 0x4E7A2A5: g_main_context_dispatch (in /usr/lib64/libglib-2.0.so.0.3800.2)
  by 0x4E7A627: ??? (in /usr/lib64/libglib-2.0.so.0.3800.2)
  by 0x4E7AA39: g_main_loop_run (in /usr/lib64/libglib-2.0.so.0.3800.2)
  by 0x4038EA: client_ready (test-gdbus-client.c:1014)
  by 0x4E9E5E0: ??? (in /usr/lib64/libglib-2.0.so.0.3800.2)
  by 0x4E9E7A5: ??? (in /usr/lib64/libglib-2.0.so.0.3800.2)
  by 0x4E9EB1A: g_test_run_suite (in /usr/lib64/libglib-2.0.so.0.3800.2)
  by 0x403614: main (test-gdbus-client.c:1058)
Address 0x5dbe5d0 is 0 bytes inside a block of size 7 free'd
  at 0x4C28577: free (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
  by 0x4E7FF7E: g_free (in /usr/lib64/libglib-2.0.so.0.3800.2)
  by 0x405B04: update_name_cache (watch.c:434)
  by 0x405C37: update_service (watch.c:593)
  by 0x4E7A2A5: g_main_context_dispatch (in /usr/lib64/libglib-2.0.so.0.3800.2)
  by 0x4E7A627: ??? (in /usr/lib64/libglib-2.0.so.0.3800.2)
  by 0x4E7AA39: g_main_loop_run (in /usr/lib64/libglib-2.0.so.0.3800.2)
  by 0x4038EA: client_ready (test-gdbus-client.c:1014)
  by 0x4E9E5E0: ??? (in /usr/lib64/libglib-2.0.so.0.3800.2)
  by 0x4E9E7A5: ??? (in /usr/lib64/libglib-2.0.so.0.3800.2)
  by 0x4E9EB1A: g_test_run_suite (in /usr/lib64/libglib-2.0.so.0.3800.2)
  by 0x403614: main (test-gdbus-client.c:1058)
gdbus: Fix crash when watch is toggled or disconnected

This partially reverts 510b32b7156625b9df737c916b7a7a5c6fb285b9 since it
still necessary to take a reference before calling dbus_watch_handle
since internally it can call watch_info_free as in the following trace:

 Invalid read of size 8
   at 0x121085: watch_func (mainloop.c:105)
   by 0x4C72694: g_main_context_dispatch (gmain.c:2539)
   by 0x4C729C7: g_main_context_iterate.isra.23 (gmain.c:3146)
   by 0x4C72DC1: g_main_loop_run (gmain.c:3340)
   by 0x120541: main (main.c:551)
 Address 0x5bbcd90 is 16 bytes inside a block of size 24 free'd
   at 0x4A079AE: free (vg_replace_malloc.c:427)
   by 0x4C7837E: g_free (gmem.c:252)
   by 0x4F708BF: dbus_watch_set_data (dbus-watch.c:614)
   by 0x4F70938: _dbus_watch_unref (dbus-watch.c:132)
   by 0x4F6E9A7: _dbus_transport_handle_watch (dbus-transport.c:884)
   by 0x4F59AFB: _dbus_connection_handle_watch (dbus-connection.c:1497)
   by 0x4F70AF9: dbus_watch_handle (dbus-watch.c:683)
   by 0x121084: watch_func (mainloop.c:103)
   by 0x4C72694: g_main_context_dispatch (gmain.c:2539)
   by 0x4C729C7: g_main_context_iterate.isra.23 (gmain.c:3146)
   by 0x4C72DC1: g_main_loop_run (gmain.c:3340)
   by 0x120541: main (main.c:551)
gdbus: Fix match rule for NameOwnerChanged

When subscribing to the D-Bus signal NameOwnerChanged from the bus driver,
specify the object path and the sender in the match rule. Otherwise, random
connections on the bus could impersonate the bus driver.
[connman] Cherry-pick upstream gdbus memory handling fixes
Merge pull request #161 from hmallat/gdbus-upstream-fixes

Gdbus upstream fixes
Merge branch 'master' of https://github.com/mer-packages/connman into remove_dns_trigger_v3