Fix build: Remove -Wold-style-cast

 libz.h has macros using old-style-cast.

Change-Id: I48f7d85805c7c34e1453c863da3c9e734a57d479
diff --git a/libziparchive/Android.mk b/libziparchive/Android.mk
index 3937449..027ad16 100644
--- a/libziparchive/Android.mk
+++ b/libziparchive/Android.mk
@@ -25,7 +25,6 @@
 LOCAL_SHARED_LIBRARIES := libutils
 LOCAL_MODULE:= libziparchive
 LOCAL_CFLAGS := -Werror -Wall
-LOCAL_CPPFLAGS := -Wold-style-cast
 include $(BUILD_STATIC_LIBRARY)
 
 include $(CLEAR_VARS)