Log Message:
Update print/mupdf to 1.7, provided by Leonardo Taccari in PR 49843.

Changes:
MuPDF 1.7 (2015-04-16)

   The 1.7 release is here!

MuPDF 1.7 RC1 (2015-04-08)

   The 1.7 release is almost here!

   Headline changes:
     * New 'Indie dev' licensing options - contact sales@artifex.com
       for more details.
     * New HTML layout engine, and (DRM-free) EPUB viewer.
     * Reduced memory usage - displaylists and internal PDF representation
       take much less memory, reducing total memory use on some files by
       over 60%.

   Important API changes:
     * Bound contexts have been removed; we now pass fz_contexts
       explicitly.
     * Reference counting of paths and text structures.

   Features:
     * Add mutool pages option.
     * Tweaked rendering to prevent feature dropout in common cases.
     * Viewer tweaks
          + Better mouse wheel handling
          + Shift-space support
          + Mouse button control of presentation mode
          + Failed reloads do not close document

   Internal changes:
     * PDF filter revamp - simpler interface.
     * Devices use derived structures rather than user pointer.
     * Sparse PDF xrefs held in more compact form.
     * New gsview viewer split out to its own repository.

   Bug fixes
     * Improved handling of broken files.
     * Fix BBoxes of Type 3 fonts.
     * Updated fonts (including greek and cyrillic).
     * Various memory leaks and crashes.
     * And many more.