Checks if we are running against MariaDB.

def _IsMariaDB(cursor):
  """Checks if we are running against MariaDB."""
  for variable in ["version", "version_comment"]:
    cursor.execute("SHOW VARIABLES LIKE %s;", (variable,))
    version = cursor.fetchone()
    if version and "MariaDB" in version[1]:
      return True
  return False