Stop using timestamps for support-annotations jar.

Bug: 37504094
Test: ./gradlew support-annotations:jar
Change-Id: Ia19074f9d46bcf7b63744d85a89824bd805bbef4
diff --git a/annotations/build.gradle b/annotations/build.gradle
index a8c2809..4bedc3f 100644
--- a/annotations/build.gradle
+++ b/annotations/build.gradle
@@ -14,6 +14,7 @@
     // below by the annotationsZip task.
     exclude('android/support/annotation/ProductionVisibility.class')
     exclude('android/support/annotation/DimensionUnit.class')
+    preserveFileTimestamps = false
 }
 
 // configuration for the javadoc to include all source sets.