Fix Bazel-JDK7 breakage on CI

src/test/java/com/google/devtools/build/lib/skyframe/TreeArtifactBuildTest.java:154: error: local variable normalOutput is accessed from within inner class; needs to be declared final
          touchFile(normalOutput);

http://ci.bazel.io/job/bazel-tests/BAZEL_VERSION=HEAD-jdk7,PLATFORM_NAME=linux-x86_64/290/console

--
MOS_MIGRATED_REVID=136588819

src/test/java/com/google/devtools/build/lib/skyframe/TreeArtifactBuildTest.java

diff --git a/src/test/java/com/google/devtools/build/lib/skyframe/TreeArtifactBuildTest.java b/src/test/java/com/google/devtools/build/lib/skyframe/TreeArtifactBuildTest.java
index 5239f06..b2359d9 100644
--- a/src/test/java/com/google/devtools/build/lib/skyframe/TreeArtifactBuildTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skyframe/TreeArtifactBuildTest.java
@@ -138,7 +138,7 @@
     TouchingTestAction actionOne = new TouchingTestAction(outOneFileOne, outOneFileTwo);
     registerAction(actionOne);
 
-    Artifact normalOutput = createDerivedArtifact("normal/out");
+    final Artifact normalOutput = createDerivedArtifact("normal/out");
     Action testAction = new TestAction(
         TestAction.NO_EFFECT, ImmutableList.of(outOne), ImmutableList.of(normalOutput)) {
       @Override