contrib: caca: Disable build on darwin OS

This does not build anymore with recent ncurses, and the caca
vlc module is also disabled by default. Thus disable
the contrib as well.

contrib/src/caca/rules.mak

@@ -2,11 +2,14 @@
 CACA_VERSION := 0.99.beta17
 CACA_URL := http://caca.zoy.org/files/libcaca/libcaca-$(CACA_VERSION).tar.gz
 
+ifndef HAVE_DARWIN_OS
 ifndef HAVE_LINUX # see VLC Trac 17251
 ifndef HAVE_WINSTORE
 PKGS += caca
 endif
 endif
+endif
+
 ifeq ($(call need_pkg,"caca >= 0.99.beta14"),)
 PKGS_FOUND += caca
 endif