fixed wrong lcs and min_best_span_pos when any expansion (expand or lemmatize) applied

git-svn-id: http://sphinxsearch.googlecode.com/svn/trunk@3990 8b96e2b9-35c5-2c16-bc47-5122d61876d4
Fixed several warnings from static cpp analyzer

git-svn-id: http://sphinxsearch.googlecode.com/svn/trunk@3991 8b96e2b9-35c5-2c16-bc47-5122d61876d4