weston: drop libunwind optional dependency

libunwind was dropped since 3.0.91, see:
https://github.com/wayland-project/weston/commit/bb707dc0fe331c9af112a0552b7aa6fde755dd83

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/weston/weston.mk

@@ -60,12 +60,6 @@ WESTON_CONF_OPTS += \
 	--disable-simple-egl-clients
 endif
 
-ifeq ($(BR2_PACKAGE_LIBUNWIND),y)
-WESTON_DEPENDENCIES += libunwind
-else
-WESTON_CONF_OPTS += --disable-libunwind
-endif
-
 ifeq ($(BR2_PACKAGE_WESTON_RDP),y)
 WESTON_DEPENDENCIES += freerdp
 WESTON_CONF_OPTS += --enable-rdp-compositor