Remove unused variable.

This is to fix the following:

  ../../../../ext/fizzbuzz/fizzbuzz.c: In function ‘fizzbuzz_evaluate’:
  ../../../../ext/fizzbuzz/fizzbuzz.c:402:11: warning: unused variable ‘result’ [-Wunused-variable]

Signed-off-by: Krzysztof Wilczynski <krzysztof.wilczynski@linux.com>