make sure that Checker calls the destroy method of FileSetCheck.

Clover is really cool, I found this bug by looking at the coverage
of AbstractFileSetCheck - clover told me that destroy was never
executed and that seemed strange to me.

src/checkstyle/com/puppycrawl/tools/checkstyle/Checker.java

@@ -208,6 +208,7 @@ public class Checker extends AutomaticBean
         for (int i = 0; i < mFileSetChecks.size(); i++) {
             FileSetCheck fileSetCheck = (FileSetCheck) mFileSetChecks.get(i);
             fileSetCheck.process(aFiles);
+            fileSetCheck.destroy();
         }
         int errorCount = mCounter.getCount();
         fireAuditFinished();

src/tests/com/puppycrawl/tools/checkstyle/FileSetCheckLifecycleTest.java

@@ -0,0 +1,50 @@
+package com.puppycrawl.tools.checkstyle;
+
+import java.io.File;
+
+import com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck;
+import com.puppycrawl.tools.checkstyle.api.Configuration;
+
+public class FileSetCheckLifecycleTest     extends BaseCheckTestCase
+{
+    protected DefaultConfiguration createCheckerConfig(Configuration aCheckConfig)
+    {
+        final DefaultConfiguration dc = new DefaultConfiguration("root");
+        dc.addChild(aCheckConfig);
+        return dc;
+    }
+
+    public static class TestFileSetCheck extends AbstractFileSetCheck
+    {
+        private static boolean destroyed = false;
+
+        public void destroy()
+        {
+            destroyed = true;
+        }
+
+        public static boolean isDestroyed()
+        {
+            return destroyed;
+        }
+
+        public void process(File[] aFiles)
+        {
+        }
+    }
+
+    public void testTranslation()
+         throws Exception
+    {
+        Configuration checkConfig = createCheckConfig(TestFileSetCheck.class);
+        Checker c = createChecker(checkConfig);
+        final String filepath = getPath("InputScopeAnonInner.java");
+
+        final String[] expected = {
+        };
+        verify(c, filepath, filepath, expected);
+
+        assertTrue("destroy() not called by Checker", TestFileSetCheck.isDestroyed());
+    }
+
+}