main: don't crash if DBus is not running
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
1 file changed
