added support for negative number as well as zero for vector product (#Issue 6)

[ahiliitb]

#6

[LoPA607]

Hi ,
Good to see your enthu to solve problems but
There is a small issue in your code
log_correct.cpp: In function ‘std::pair<int, int> count_negative_and_zero(int*, int, int)’:
log_correct.cpp:29:78: error: ‘negative_count’ appears more than once in data clauses
29 | #pragma omp parallel for private(negative_count, zero_count) reduction(+:negative_count, zero_count) num_threads(num_threads)
| ^~~~~~~~~~~~~~
log_correct.cpp:29:94: error: ‘zero_count’ appears more than once in data clauses
29 | #pragma omp parallel for private(negative_count, zero_count) reduction(+:negative_count, zero_count) num_threads(num_threads)
please rectify it .