Always include CLEAR_VARS in Android.mk

Otherwise build may terminate with error message reads

  ... Cannot set module stem for a library

Change-Id: I4448b7b56eb7c26dd079a429c1a864b7abe5256c
diff --git a/lib32/Android.mk b/lib32/Android.mk
index e900499..dbb512b 100644
--- a/lib32/Android.mk
+++ b/lib32/Android.mk
@@ -14,6 +14,8 @@
 
 LOCAL_PATH := $(call my-dir)
 
+include $(CLEAR_VARS)
+
 LOCAL_PREBUILT_LIBS := \
           libbfd.a \
           libiberty.a \