Bring tests/ over from Brew dist-git

Signed-off-by: Vladis Dronov <vdronov@redhat.com>

.gitignore

@@ -1 +1 @@
-/xxhash-0.8.1.tar.gz
+/xxhash-*.tar.gz

tests/nulltest.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+# xxhash runs tests at build stage. if tests fail a build fails. no need to duplicate.
+
+echo XXHASH nulltest is PASS
+exit 0

tests/tests.yml

@@ -0,0 +1,10 @@
+---
+- hosts: localhost
+  roles:
+  - role: standard-test-basic
+    tags:
+    - classic
+    tests:
+    - nulltest:
+        dir: .
+        run: nulltest.sh