attempt to fix sdk build

Change-Id: I94f32a9a7abccb52487bb9ff5e286faa4acfceff
diff --git a/libs/androidfw/Android.mk b/libs/androidfw/Android.mk
index 5dc77f3..c5f8a87 100644
--- a/libs/androidfw/Android.mk
+++ b/libs/androidfw/Android.mk
@@ -52,6 +52,9 @@
 
 LOCAL_MODULE_TAGS := optional
 
+LOCAL_C_INCLUDES := \
+	external/zlib
+
 include $(BUILD_HOST_STATIC_LIBRARY)