[tlbuild] Patch for making poppler compile on NetBSD

[Marc Baudoin]

Hi,

Since its update a few days ago, poppler doesn't compile on
NetBSD.  To make it compile again, I had to add these few lines
in libs/poppler/poppler-src/goo/gfile.h:

#if defined(__NetBSD__)
#include <time.h>
#endif