Security update for libX11 (moderate)

This update for libX11 fixes the following security issues:

• CVE-2018-14599: The function XListExtensions was vulnerable to an
  off-by-one error caused by malicious server responses, leading to DoS or
  possibly unspecified other impact (bsc#1102062)
• CVE-2018-14600: The function XListExtensions interpreted a variable as
  signed instead of unsigned, resulting in an out-of-bounds write (of up
  to 128 bytes), leading to DoS or remote code execution (bsc#1102068)
• CVE-2018-14598: A malicious server could have sent a reply in which the
  first string overflows, causing a variable to be set to NULL that will
  be freed later
  on, leading to DoS (segmentation fault) (bsc#1102073)

This update was imported from the SUSE:SLE-15:Update update project.