mariadb: security bump to 10.1.37

mariadb: security bump to 10.1.37

Notable Changes (copied from release notes):

  Various fixes from MySQL 5.6.42: MDEV-17533, MDEV-17532, MDEV-17531
  MDEV-16465: fixed a bug with DDL and FOREIGN KEY
  Fulltext index fixes:
    MDEV-12547: extended the range of innodb_ft_result_cache_limit on 64-bit systems
    MDEV-16865: InnoDB fts_query() ignores KILL
  Fixes for the following security vulnerabilities:
    CVE-2018-3282
    CVE-2016-9843
    CVE-2018-3174
    CVE-2018-3143
    CVE-2018-3156
    CVE-2018-3251

OpenWrt changes:
  - dropped obsolete ucontext patch (issue fixed upstream)
  - refreshed 130-c11_atomics.patch

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>