med3
pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
pm = med3(pm - d, pm, pm + d, cmp, thunk);
pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
pm = med3(pl, pm, pn, cmp, thunk);
static inline char *med3(char *, char *, char *, cmp_t *, void *);
pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
pm = med3(pm - d, pm, pm + d, cmp, thunk);
pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
pm = med3(pl, pm, pn, cmp, thunk);
static inline char *med3(char *, char *, char *, cmp_t *, void *);