Simplify a bit of code by using string-suffix-p

Author: bbatsov

cider-test.el

@@ -563,8 +563,7 @@ The default implementation uses the simple Leiningen convention of appending
 This uses the Leiningen convention of appending '-test' to the namespace name."
   (when ns
     (let ((suffix "-test"))
-      ;; string-suffix-p is only available in Emacs 24.4+
-      (if (string-match-p (rx-to-string `(: ,suffix eos) t) ns)
+      (if (string-suffix-p suffix ns)
           ns
         (concat ns suffix)))))