Don't build 32-bit host libadb.

Change-Id: Ib6ad3db2dc160273d20fa14e0820f29ed649d75a
diff --git a/Android.mk b/Android.mk
index e271a63..df0c7a1 100644
--- a/Android.mk
+++ b/Android.mk
@@ -118,6 +118,8 @@
 
 ifeq ($(HOST_OS),windows)
     LOCAL_C_INCLUDES += development/host/windows/usb/api/
+else
+    LOCAL_MULTILIB := 64
 endif
 
 include $(BUILD_HOST_STATIC_LIBRARY)