Log Message:
Update sphinxsearch 2.1.9.

Changes:
- fixed #1994, parsing of empty JSON arrays
- fixed #1987, handling of index_exact_words with AOT morphology
  and infixes
- fixed #1984, teaching HTML parser to handle hex numbers
- fixed #1983, master and agents networking issue
- fixed #1977, escaping of characters doesn't work with exceptions
- fixed #1968, parsing of WEIGHT() function (queries to distributed
  indexes affected)