Remove update icon cache as it is a sandbox access violation.
We do this in the ebuild by ourselves instead.

--- a/driver/Makefile.in
+++ b/driver/Makefile.in
@@ -564,7 +564,6 @@ install-gnome:: $(LOGO)
         fi

 install-gnome:: uninstall-old-gnome-icons
-install-gnome:: update-icon-caches

 update-icon-caches::
        @for f in /usr/share/icons/index.theme