Security update for libXfont (important)

libXFont was updated to fix three vulnerabilities when parsing BDF files
(bnc#921978)

As libXfont is used by the X server to read font files, and an
unprivileged user with access to the X server can tell the X server to
read a given font file from a path of their choosing, these
vulnerabilities have the potential to allow unprivileged users to run code
with the privileges of the X server.

The following vulnerabilities were fixed:

• The BDF parser could allocate the a wrong buffer size, leading to out of
  bound writes (CVE-2015-1802)
• The BDF parser could crash when trying to read an invalid pointer
  (CVE-2015-1803)
• The BDF parser could read 32 bit metrics values into 16 bit integers,
  causing an out-of-bound memory access though integer overflow
  (CVE-2015-1804)