Fix function declaration of some modifiers

Those functions did not use evaluation context.

Also fixed lots of unused variables warnings caused by commented out code which
needs to be ported away from DerivedMesh and to evaluation context.

source/blender/python/mathutils/mathutils_bvhtree.c

@@ -1098,6 +1098,8 @@ static DerivedMesh *bvh_get_derived_mesh(
 			}
 		}
 	}
+#else
+	UNUSED_VARS(funcname, scene, ob, use_deform, use_render, use_cage);
 #endif
 
 	return NULL;