[poppler] Poppler 21.12.0 released

[Albert Astals Cid]

Available from
http://poppler.freedesktop.org/poppler-21.12.0.tar.xz

The tarball is signed at http://poppler.freedesktop.org/poppler-21.12.0.tar.xz.sig with my key
http://pgp.rediris.es:11371/pks/lookup?op=get&search=0xCA262C6C83DE4D2FB28A332A3A6A4DB839EAA6D7

Release 21.12.0:
core:
 * Add API to add images
 * CairoOutputDev: Fix de-duping of Flate images
 * Fix crash on broken files when using non-default ENABLE_ZLIB_UNCOMPRESS. Issue #393
 * Minor code improvements

glib:
 * Add API for validation of signatures
 * Add API to read/save to file descriptor

utils:
 * pdftohtml: Reduce sensitivity of duplicate detection. Issue #1117

build system:
 * Increase C++ standard to 17

This release was brought to you by Adrian Johnson, Albert Astals Cid, Christian Persch, Christopher Hasse, Even Rouault, Georgiy Sgibnev, Marek Kasik and everyone else that filed bugs or helped with code reviews :)

Testing, patches and bug reports welcome.

Cheers,
  Albert