biology/wfa2-lib: fix build without libomp

/wrkdirs/usr/ports/biology/wfa2-lib/work/WFA2-lib-2.3.5/tools/align_benchmark/align_benchmark.c:32:10: fatal error: 'omp.h' file not found

32 | #include <omp.h>
   |          ^~~~~~~

1 error generated.