ws: Drain the GMainContext when stopping the MockService

Otherwise references are held by outstanding sounces in the
GMainContext. If a GDBusConnection is leaked then g_test_dbus_down()
will hang for 30 seconds and fail waiting for it to go away.

Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
Makefile.am: Don't use libtool for producing binaries

Ding dong the witch is dead.

We don't produce libraries and don't need to get involved
in ugliness like libtool.

We don't need to install libcockpit at all.
Makefile.am: Build main Makefile first

Helps speed up iterating through build or test failures