Fix build, by using external/zlib instead of system zlib

Change-Id: I22f72f7c21f0c3f7b40deeca429af39453dfdc51

Android.mk

@@ -347,6 +347,7 @@ LOCAL_SRC_FILES := $(COMPILER_SRC_FILES)
 
 LOCAL_C_INCLUDES := \
     $(LOCAL_PATH)/android \
+    external/zlib \
     $(LOCAL_PATH)/src
 
 LOCAL_STATIC_LIBRARIES += libz