[master] added post-test cleanup for an included zone file in query test.

this fixes unittest failure on a static-link build (not really
static-link specific, but this happens if sqlite3 tests are skipped).

beyond the super trivial level, but I'm sure and have confirmed it fixes
the problem, so I'm committing it now.

src/bin/auth/tests/query_unittest.cc

@@ -862,6 +862,15 @@ protected:
         list_ = createDataSrcClientList(GetParam(), memory_client);
     }
 
+    virtual void TearDown() {
+        // make sure to clear the commonly included zone file to prevent
+        // any remaining contents from affecting the next test.
+        ASSERT_EQ(0, std::system(INSTALL_PROG " -c " TEST_OWN_DATA_DIR
+                                 "/example-common-inc-template.zone "
+                                 TEST_OWN_DATA_BUILDDIR
+                                 "/example-common-inc.zone"));
+    }
+
     virtual ~QueryTest() {
         // Make sure we reset the hash creator to the default
         setNSEC3HashCreator(NULL);