weston: Change path for default terminal launcher to ${prefix}/bin

If you don't have anything at ~/.config/weston-desktop-shell.ini and
have weston installed somewhere other than /usr, then this patch will
help.

Cheers,

Signed-off-by: Rodney Lorrimar <rodney@rodney.id.au>
diff --git a/clients/desktop-shell.c b/clients/desktop-shell.c
index db41568..a181e3b 100644
--- a/clients/desktop-shell.c
+++ b/clients/desktop-shell.c
@@ -698,7 +698,7 @@
 	wl_list_for_each(output, &desktop->outputs, link)
 		panel_add_launcher(output->panel,
 				   DATADIR "/weston/terminal.png",
-				   "/usr/bin/weston-terminal");
+				   BINDIR "/weston-terminal");
 }
 
 int main(int argc, char *argv[])