Patch for csvbreak.c

[bobhairgrove]

Issues addressed:

1. -Wunuset-parameter warnings resolved;
2. Inserted calls to csv_free() at appropriate places if exit() or err() was called due to an error;
3. Fixed missing fclose() in main() for infile (if infile != stdin).

(Note: I did not test all of the options. Command line used was:
csvbreak -f 1 -h -r -P ../OUT_ [outfile]
)

csvbreak_patch.txt