avoid redundant recursion for executing tests

avoid redundant recursion for executing tests

* Makefile.decl: make sure that check-local does not depend on a
  recursive target for the tests. This way check can recurse and call
  check-local in each folder which then invokes test-cwd. This will
  make sure that a toplevel check-local doesn't recurse into subfolders
  as well. The was resulting in test being run twice (for "/tests"), tree
  times (e.g. for "/gtk/tests") and potentially more often