move pod tests into xt/

diff --git a/t/03podcoverage.t b/xt/pod-coverage.t
similarity index 100%
rename from t/03podcoverage.t
rename to xt/pod-coverage.t

diff --git a/t/02pod.t b/xt/pod-syntax.t
similarity index 100%
rename from t/02pod.t
rename to xt/pod-syntax.t