[poppler] Poppler 0.56.0 released

[Albert Astals Cid]

Available from
http://poppler.freedesktop.org/poppler-0.56.0.tar.xz

Changes against 0.55.0 include:
core:
 * FormFieldButton::setState() shouldn't check the field is readOnly
 * Fix crashes on multiple broken files

utils:
 * pdfunite: Fix crash with broken documents. Bugs #101153 #101149

This release was brought to you by Albert Astals Cid, Even Rouault, Hans-
Ulrich Jüttner, Jose Aliste

Testing, patches and bug reports welcome.

Cheers,
  Albert