Cleanup: CMake: clean sequencer's CMakeLists.txt

- Remove animrig include, replace with lib dependency
- mark internal include as private

Pull Request: https://projects.blender.org/blender/blender/pulls/132502

source/blender/sequencer/CMakeLists.txt

@@ -4,9 +4,7 @@
 
 set(INC
   PUBLIC .
-  intern
-  ../animrig
-
+  PRIVATE intern
 )
 
 set(INC_SYS
@@ -86,6 +84,7 @@ set(SRC
 )
 
 set(LIB
+  PRIVATE bf::animrig
   PRIVATE bf::blenfont
   PRIVATE bf::blenkernel
   PRIVATE bf::blenlib