Security update for GraphicsMagick (important)

This update for GraphicsMagick fixes the following issues:

Security issues fixed:

• CVE-2017-16546: Fix ReadWPGImage function in coders/wpg.c that could
  lead to a denial of service (bsc#1067181).
• CVE-2017-14342: Fix a memory exhaustion vulnerability in ReadWPGImage in
  coders/wpg.c that could lead to a denial of service (bsc#1058485).
• CVE-2017-16669: Fix coders/wpg.c that allows remote attackers to cause a
  denial of service via crafted files (bsc#1067409).
• CVE-2017-16545: Fix the ReadWPGImage function in coders/wpg.c as a
  validation problems could lead to a denial of service (bsc#1067184).
• CVE-2017-14341: Fix infinite loop in the ReadWPGImage function
  (bsc#1058637).
• CVE-2017-13737: Fix invalid free in the MagickFree function in
  magick/memory.c (tiff.c) (bsc#1056162).
• CVE-2017-11640: Fix NULL pointer deref in WritePTIFImage() in
  coders/tiff.c (bsc#1050632).