Fix return value of big_int_hamming_distance()
Fix return value of big_int_hamming_distance()

Caught by gcc 4.6.1:

	libbig_int/src/bitset_funcs.c: In function ‘big_int_hamming_distance’:
	libbig_int/src/bitset_funcs.c:639:9: error: variable ‘result’ set but not used [-Werror=unused-but-set-variable]

mlafeldt/cb2util,mlafeldt/cb2util,mlafeldt/cb2util