meson: build caca plugin

https://bugzilla.gnome.org/show_bug.cgi?id=784134

ext/libcaca/meson.build

@@ -0,0 +1,11 @@
+libcaca_dep = dependency('caca', required : false)
+
+if libcaca_dep.found()
+  library('gstcacasink', 'gstcacasink.c',
+    c_args : gst_plugins_good_args,
+    link_args : noseh_link_args,
+    include_directories : [configinc],
+    dependencies : [gstvideo_dep, gstbase_dep, libcaca_dep],
+    install : true,
+    install_dir : plugins_install_dir)
+endif

ext/meson.build

@@ -4,7 +4,7 @@ subdir('flac')
 subdir('gdk_pixbuf')
 subdir('jack')
 subdir('jpeg')
-# subdir('libcaca')
+subdir('libcaca')
 # FIXME: dv plugin fails to link with msvc, wants pthread.lib
 if cc.get_id() != 'msvc'
   subdir('dv')