Update sphinxsearch to 2.1.4.

- WEIGHT() can now be used directly in the ORDER BY clause, until now
  it was necessary to use a declared alias in the SELECT statement
- SHOW PROFILE works for fullscan queries as well ( queries without
  a fulltext match)
- added –with-re2-includes and –with-re2-libs for specifying RE2 engine
  paths at compilation
- fixed an issue on indexes with more than 255 attributes ( bug #1778)
- fixed missing results in queries with quorum operator on indexes
  with lemmatization (bug #1796)
- fixed incorrect results in queries on indexes with wordforms,
  lemmatization and enabled star (bug #1780)