fix libjpeg include path specification for MuPDF
fix libjpeg include path specification for MuPDF

I'm actually not sure why this has worked before. The error crept up
the first time for me here.

frankyifei/koreader-base,NiLuJe/koreader-base,Hzj-jie/koreader-base,houqp/koreader-base,Frenzie/koreader-base,koreader/koreader-base,houqp/koreader-base,NiLuJe/koreader-base,Frenzie/koreader-base,apletnev/koreader-base,Hzj-jie/koreader-base,Frenzie/koreader-base,Frenzie/koreader-base,houqp/koreader-base,apletnev/koreader-base,koreader/koreader-base,houqp/koreader-base,koreader/koreader-base,frankyifei/koreader-base,Hzj-jie/koreader-base,koreader/koreader-base,Hzj-jie/koreader-base,apletnev/koreader-base,NiLuJe/koreader-base,frankyifei/koreader-base,NiLuJe/koreader-base,apletnev/koreader-base,frankyifei/koreader-base