Fix null check for BaseObj.equals.

Change-Id: I4f060697db175cbf0b5617c1220db853bbe53f1f
diff --git a/rs/java/android/renderscript/BaseObj.java b/rs/java/android/renderscript/BaseObj.java
index b386dd7..1372ab7 100644
--- a/rs/java/android/renderscript/BaseObj.java
+++ b/rs/java/android/renderscript/BaseObj.java
@@ -181,6 +181,10 @@
         if (this == obj)
             return true;
 
+        if (obj == null) {
+            return false;
+        }
+
         if (getClass() != obj.getClass()) {
             return false;
         }