Gallery2 : only build for 32-bit

Gallery2 depends on librsjni, which currently only builds for arm,
mips and x86.

Change-Id: I4fbf12f525941b75a7b47581db2ba43cf1abbbeb
diff --git a/Android.mk b/Android.mk
index b814907..52d45ba 100644
--- a/Android.mk
+++ b/Android.mk
@@ -37,6 +37,8 @@
 
 LOCAL_PROGUARD_FLAG_FILES := proguard.flags
 
+LOCAL_MULTILIB := 32
+
 include $(BUILD_PACKAGE)
 
 include $(call all-makefiles-under, jni)