LineageParts: Keep SEARCH_INDEX_DATA_PROVIDER()

 * This allows reflection to actually work on 11.

Change-Id: Ib20a50b2cfda353568b5e99f17732e28012fe0fb
diff --git a/proguard.flags b/proguard.flags
index 6724bc5..9de6495 100644
--- a/proguard.flags
+++ b/proguard.flags
@@ -29,3 +29,7 @@
     public <init>(android.content.Context, android.util.AttributeSet);
 }
 
+# Keep specific fields used via reflection.
+-keepclassmembers class * {
+    public static ** SEARCH_INDEX_DATA_PROVIDER;
+}