NoiseField: Force 32bit

This package contains older Renderscript code that can only run in
32bit mode.

Change-Id: I12d9c174a3370c029f1bcbd8a927b1b3a7328ea7
diff --git a/Android.mk b/Android.mk
index 158a43a..822ad53 100644
--- a/Android.mk
+++ b/Android.mk
@@ -27,4 +27,7 @@
 
 LOCAL_PROGUARD_FLAG_FILES := proguard.cfg
 
+# Renderscript and sdk version < 21, 32bit only.
+LOCAL_MULTILIB := 32
+
 include $(BUILD_PACKAGE)