"set-scroll-adjustments" as special, and set their signal ids into
GtkWidgetClass::set_scroll_adjustments_signal.  This makes it
possible to implement natively-scrollable widgets in perl.

This approach assumes the name name of the signal instead of
following the completely generic approach taken by gtk+.  The
idea is to hide some of the hackishness of the rather clunky,
pre-GInterface scheme from perl developers.

svn path=/trunk/; revision=1612