wayland: add necessary dependencies to fix build error

add libffi into DEPENDS to fix following build error:
| checking for FFI... no
| configure: error: Package requirements (libffi) were not met:
|
| No package 'libffi' found

Change-Id: I642012fb52ef62d1910830ad4c842cd664297b92
Signed-off-by: Zhenhua Luo <zhenhua.luo@freescale.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Open-webOS-DCO-1.0-Signed-off-by: Martin Jansa <martin.jansa@lge.com>
Reviewed-on: https://g2g.palm.com/1930
Reviewed-by: Martin Jansa <Martin.Jansa@lge.com>
Tested-by: Martin Jansa <Martin.Jansa@lge.com>
Reviewed-by: Susan Montooth <susan.montooth@lge.com>
wayland: only build the scanner in wayland-native

We only build wayland-native for the scanner, so disable the bits we don't
actually need.  This gives us a small speed up but importantly should allow
wayland-native to compile on older hosts such as CentOS 5 which currently fails.

[ YOCTO #4245 ]

Change-Id: Ie93811d88683882528e35c6e8b9d9a65239b0fc8
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Open-webOS-DCO-1.0-Signed-off-by: Martin Jansa <martin.jansa@lge.com>
Reviewed-on: https://g2g.palm.com/1931
Reviewed-by: Martin Jansa <Martin.Jansa@lge.com>
Tested-by: Martin Jansa <Martin.Jansa@lge.com>
Reviewed-by: Susan Montooth <susan.montooth@lge.com>