Fix downloadDx string condition.

Bug:
Change-Id: Ie2dc1584ad21cd09ad760be557792d6676625151
diff --git a/build.gradle b/build.gradle
index 225d87a..e743a08 100644
--- a/build.gradle
+++ b/build.gradle
@@ -295,7 +295,7 @@
 task downloadDx {
     cloudDependencies.each { entry ->
         entry.value.each { entryFile ->
-            if (entryFile.contains("dx.tar")) {
+            if (entryFile.endsWith("/dx")) {
                 dependsOn "download_deps_${entry.key}/${entryFile}"
             }
         }