Merge branch 'rs/qsort-s'

A few codepaths had to rely on a global variable when sorting elements of an array because sort(3) API does not allow extra data to be passed to the comparison function. Use qsort_s() when natively available, and a fallback implementation of it when not, to eliminate the need, which is a prerequisite for making the codepath reentrant. * rs/qsort-s: ref-filter: use QSORT_S in ref_array_sort() string-list: use QSORT_S in string_list_sort() perf: add basic sort performance test add QSORT_S compat: add qsort_s()