dbus_init() currently does not check for the g_dbus object being
properly initialized and this leads to crashes when dbus is not yet
running.
Ensure g_dbus is properly initialized and return false otherwise.
In this case the caller can understand that something went wrong and
stop the initialization procedure.
Program received signal SIGSEGV, Segmentation fault.
0x00005555555bc089 in l_dbus_add_service_watch (dbus=0x0,
name=0x5555555e5b0a "org.ofono",
connect_func=0x5555555aa81e <ofono_found>,
disconnect_func=0x5555555aa8e6 <ofono_disappeared>,
user_data=0x0, destroy=0x0) at ell/dbus.c:1621
1621 if (!dbus->name_cache)
(gdb) bt
name=0x5555555e5b0a "org.ofono",
connect_func=0x5555555aa81e <ofono_found>,
disconnect_func=0x5555555aa8e6 <ofono_disappeared>,
user_data=0x0, destroy=0x0) at ell/dbus.c:1621
user_data=0x0) at ell/plugin.c:115
function=0x5555555b40fd <plugin_start>,
user_data=0x0) at ell/queue.c:441
version=0x0) at ell/plugin.c:201
src/plugin.c:82
src/main.c:417
Move the calling of the *_shutdown functions from the signal handler to
a new public function, and use that function inside the DBus disconnect
handler to make sure resources are cleanly released.
It seems until now dbus.c would always connect to dbus-1 (unless
DBUS_SESSION_BUS_ADDRESS pointed at kdbus) and passing -K only made
iwd create a kdbus bus and not use it. Now use ell to actually use
kdbus instead of dbus-1 with -K. Don't use the src/kdbus.c functions
that duplicate ell functionality. As a side effect the connection
description and the bloom sizes are now the ell defaults.
