Switch to libpng_ndk to remove platform library dependency

Bug: 26513978
Change-Id: I4cb929149264adccdaf3de0f0f57a1e6b64921b5
diff --git a/Android.mk b/Android.mk
index a769d34..0183bb0 100644
--- a/Android.mk
+++ b/Android.mk
@@ -734,10 +734,12 @@
 		liblog \
 		libm \
 		libc \
-		libpng \
 		libz \
 		libdl
 
+LOCAL_STATIC_LIBRARIES := \
+		libpng_ndk \
+
 LOCAL_CFLAGS += \
 	$(deqp_compile_flags) \
 	-Wno-error=date-time