Fix for fuzzystrmatch

Hacker,

I found two issues in fuzzystrmatch contrib.
1) Incorrect s_data shift in levenshtein calculation with threshold with
multibyte characters. "i" index was used instead of "start_column".
2) Missing dependency of fuzzystrmatch.o on levenshtein.c

Patch is attached.

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With best regards,
Alexander Korotkov.