Java: add old generateVdl dependency back

Without it, presubmit tests fail due to timing issues.

(Thanks to sjr@ for finding the problem.)

Change-Id: I9fd13fbf7dfd07848371f34df04d91910e899122
diff --git a/lib/build.gradle b/lib/build.gradle
index 602e1b3..2ed0b9a 100644
--- a/lib/build.gradle
+++ b/lib/build.gradle
@@ -105,6 +105,7 @@
 }
 
 tasks.'processResources'.dependsOn(generateVdl)
+tasks.'compileJava'.dependsOn(generateVdl)
 
 task checkVanadiumEnvironment {
     VanadiumEnvironment.getVanadiumEnvironment()