fix(rack): use static inline for tcp_hw_highest_rate to fix -O0 link failure

Upstream FreeBSD 15.0 declares tcp_hw_highest_rate with GNU89 `inline`
(no `static`); under -O2 it is inlined away, but under -O0 (DEBUG) it
emits external references with no out-of-line definition in libfstack.a,
breaking example/ and app/nginx linking. Align with the same header's
other inline helpers which all use `static inline`.

Author: jfb8856606

freebsd/netinet/tcp_ratelimit.h

@@ -105,7 +105,7 @@ struct tcpcb;
 					 * shows up in your sysctl tree
 					 * this can be big.
 					 */
-uint64_t inline
+static uint64_t inline
 tcp_hw_highest_rate(const struct tcp_hwrate_limit_table *rle)
 {
 	return (rle->ptbl->rs_rlt[rle->ptbl->rs_highest_valid].rate);