data races in smith-waterman code

[chunhualiao]

https://github.com/TheFighters/Smith-Waterman/blob/master/omp_smithW.c

Default size does not trigger tools to report errors.

Data races are reported when 2048x2048 size is given.

    //Updates maximum score to be used as seed on backtrack
    if (max > H[*maxPos]) {
        #pragma omp critical
        *maxPos = index;
    }

Need to add this new pattern.

[peihunglin]

microbenchmark added.