Security update for glib2 (moderate)

This update for glib2 fixes the following issues:

Security issues fixed:

• CVE-2018-16428: Do not do a NULL pointer dereference (crash). Avoid
  that, at the cost of introducing a new translatable error message
  (bsc#1107121).
• CVE-2018-16429: Fixed out-of-bounds read vulnerability
  ing_markup_parse_context_parse() (bsc#1107116).

Non-security issue fixed:

• various GVariant parsing issues have been resolved (bsc#1111499)

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