Use gradle configuration cache

This greatly reduce the execution time (2.3 seconds down to 0.9 for no-op build)

The dependency is neccesary for the configuration cache to not throw up on error prone

Change-Id: I535da050cb5d4c6d36cb2d92998485e97f0ea1a1
diff --git a/d8_r8/gradle.properties b/d8_r8/gradle.properties
index 1de43f9..35bcb0b 100644
--- a/d8_r8/gradle.properties
+++ b/d8_r8/gradle.properties
@@ -11,6 +11,7 @@
 
 org.gradle.parallel=true
 org.gradle.caching=true
+org.gradle.configuration-cache=true
 
 # Do not download any jdks or detect them. We provide them.
 org.gradle.java.installations.auto-detect=false