explicitely add annotationProcessor dependency

required by Gradle 5.0 to have annotation processors active.

Test: Existing
Bug: N/A
Change-Id: Ia2a54d1f5c7ae491db833277a4189f3210589307
diff --git a/build.gradle b/build.gradle
index b783256..70fd39f 100644
--- a/build.gradle
+++ b/build.gradle
@@ -30,6 +30,7 @@
 // these have to match the dependencies found in Android.mk
 dependencies {
     compileOnly 'com.google.code.findbugs:jsr305:3.0.1'
+    annotationProcessor 'com.google.auto.value:auto-value:1.3'
     compileOnly 'com.google.auto.value:auto-value:1.3'
     compileOnly 'com.google.errorprone:error_prone_annotations:2.0.18'
 
@@ -69,4 +70,3 @@
 artifacts {
     fatJar fatJarCreator
 }
-