Bug #19606: ssl variables are not displayed in show variables
Bug #19616: log_queries_not_using_indexes  is not listed in show variables

  Make basedir, datadir, tmpdir, log_queries_not_using_indexes, ssl_ca,
  ssl_capath, ssl_cert, ssl_cipher, and ssl_key all available both from
  SHOW VARIABLES and as @@variables.

  As a side-effect of this change, log_queries_not_using_indexes can
  be changed at runtime (but only globally, not per-connection).