Update print/cups-filters to 1.17.2

Changes:
CHANGES IN V1.17.2
- libcupsfilters: Fixed outstanding bug in PCLm with JPEG (DCT)
  compression. Now PCLm support is completely working.

CHANGES IN V1.17.1
- libcupsfilters: Added direct PNG printing to the PPD
  generator, the one of CUPS has it, too.
- libcupsfilters: In the PPD file generator renamed the option
  "cupsPrintQuality" into the IPP name "print-quality" as CUPS
  does not update the "print-quality=4" entry in the filter
  command line based on the setting of "cupsPrintQuality"
  (CUPS issue #5090).
- libcupsfilters: Completely redone the way how to determine
  the resolutions to use for the default resolution and print
  quality option in the PPDs generated for IPP
  printers. Resolution lists from IPP attributes are now read
  into sorted, duplicate-free lists with wrong resolutions
  removed or fixed. Resolutions actually used are the common
  ones between the supported PDLs, PDls with inferior maximum
  resolution or with broken resolution list are skipped
  (Debian bug #868360, Ubuntu bug #1712019, CUPS issue #5088,
  CUPS issue #5091).
- rastertopdf: Prefer RLE compression instead of Flate as
  there are HP printers where Flate is buggy.
- Build system: Fixed help mesage for "--enable-driverless"
  configure option (Bug #1405).

CHANGES IN V1.17.0
- rastertopdf, rastertopclm, driverless, cups-browsed,
  libcupsfilters: Added support for the PCLm output format for
  driverless printing on Mopria and Wi-Fi Direct
  printers. This is the Google Summer of Code 2017 project of
  Sahil Arora (sahilarora dot 535 at gmail dot com). Thank you
  very much for your great work!  The PCLm support requires
  QPDF 7.0.0 or later.

CHANGES IN V1.16.4
- Build system: Switched over to C11 standard with GNU
  extensions (-std=gnu11).
- Build system: Removed -pedantic flag as it is only needed
  for compatibility with commercial compilers like the ones of
  Windows (and we use GNU extensions anyway).
- libfontembed, texttopdf: reverted removal of anonymous
  union.

CHANGES IN V1.16.3
- libfontembed: Reverted unneeded soname change.

CHANGES IN V1.16.2
- README: Minimum CUPS requirement of cups-filters is CUPS
  1.4.x.  It does not build with earlier CUPS versions (Bug
  #993).
- driverless, foomatic-rip: Create relative symbolic links.
- All C/C++ files: Silenced all compiler warnings, at least
  the ones appearing when building on Ubuntu Linux 17.10 with
  GCC 7.1.0.
- README: Updated the introduction section to reflect the
  current functionality of cups-filters, and the build
  requirements for the Poppler-based filters (C++11: Bug
  #1404, Build configuration of Poppler: Bug #1257). Thanks to
  Roland Hieber (r dot hieber at pengutronix dot de) to find
  out about this.
- pdftoopvp, bannertopdf, pdftoraster: Build with C++11
  standard as some features of this standard are needed by
  these filters (or by Poppler). Thanks to Roland Hieber (r
  dot hieber at pengutronix dot de) for the patch (Bug #1404).

(leot)