Bump libpng to 1.6.37
Bump libpng to 1.6.37

NiLuJe/koreader-base,Frenzie/koreader-base,koreader/koreader-base,Frenzie/koreader-base,koreader/koreader-base,Frenzie/koreader-base,koreader/koreader-base,Frenzie/koreader-base,NiLuJe/koreader-base,NiLuJe/koreader-base,NiLuJe/koreader-base,koreader/koreader-base