tcp: add missing static keywords

Without them compilation with -O0 would produce kernel modules
that depend on symbol that doesn't exist.

sys/netinet/tcp_hpts.h

@@ -192,7 +192,7 @@ tcp_tv_to_lusectick(const struct timeval *sv)
 
 extern int32_t tcp_min_hptsi_time;
 
-__inline int32_t
+static inline int32_t
 get_hpts_min_sleep_time(void)
 {
 	return (tcp_min_hptsi_time + HPTS_TICKS_PER_SLOT);

sys/netinet/tcp_stacks/tcp_rack.h

@@ -109,13 +109,13 @@ struct deferred_opt_list {
  * as well.
  */
 
-inline uint64_t
+static inline uint64_t
 rack_to_usec_ts(struct timeval *tv)
 {
 	return ((tv->tv_sec * HPTS_USEC_IN_SEC) + tv->tv_usec);
 }
 
-inline uint32_t
+static inline uint32_t
 rack_ts_to_msec(uint64_t ts)
 {
 	return((uint32_t)(ts / HPTS_MSEC_IN_SEC));