clutter_init() fails under normal circumstances like
being unable to open a display connection, so it shouldn't
be handled with g_error() producing a core dump.
Clutter consistently produces an error message when
clutter_init() fails, so we don't need to print out any
error message.
https://bugzilla.gnome.org/show_bug.cgi?id=643910
ST makes use of GTK+ for input methods and for icon themes; therefore
we have need to initialize GTK+ in order to test these parts of Clutter.
Instead of LD_PRELOADING our module, use a separately compiled executable
that links to the UI components in GNOME Shell, initializes Clutter and
GTK+ and hooks them together.
Getting all the symbols from St and the GUI components exported for
use via GJS requires a bit of contortion: we need to actually link the
St convenience library into a shared library and link the executable
to that since there is no way with libtool to take a convenience library
and put all its symbols into an executable --whole-archive style.
https://bugzilla.gnome.org/show_bug.cgi?id=633657
