Drop gnome-icon-theme dependency

As far as I can tell, Evince required only 3 icons from
gnome-icon-theme, 'object-rotate-left', 'object-rotate-right' and
'x-office-presentation'.

This patch adds copies for these icons from gnome-icon-theme-2.24.

It also removes the compile-time check for gnome-icon-theme on
all platforms execpt gnome.

Note, when gnome-icon-theme is installed, the icons from that theme take
precedence over the icons from this patch. Therefore, evince uses the icons
from this patch only as a backup when no gnome-icon-theme is installed.

All added icons are copied from gnome-icon-theme-2.24, which is licensed
under GNU GPLv2.