desktop-shell: Use 'surface-local' to correct grammar
desktop-shell: Use 'surface-local' to correct grammar

Correct the pluralization by simplifying with 'surface-local'.

See https://lists.freedesktop.org/archives/wayland-devel/2016-April/028249.html.

Signed-off-by: Yong Bakos <d0d6c2a9047d8c98cd8ce1e9b46eb851dcd10a82@humanoriented.com>
Reviewed-by: Bryce Harrington <bdb14cfc1ab8d24e13de84adc40b41ae60c13bd1@osg.samsung.com>

Gnurou/weston,sir-murray/weston,krezovic/weston,krezovic/weston,giucam/weston,sir-murray/weston,giucam/weston,Gnurou/weston