Updated mupdf packages fix security vulnerability

A flaw was discovered in the pdf_load_mesh_params() function allowing out-of-bounds write access to memory locations. With carefully crafted input, that could trigger a heap overflow, resulting in application crash or possibly having other unspecified impact (CVE-2016-6525). Also, mupdf already contained the X11 viewer /usr/bin/mupdf-x11 but no mupdf binary to match the man page instructions. A symlink to mupdf-x11 now provides this (mga#19105).