Module is dead code: cannot link because all engine symbols are defined only in non-compilable netflow.c

Summary

ng_netflow.c references 6 functions defined only in netflow.c: ng_netflow_cache_init (:188 constructor) ng_netflow_expire (:278 callout) ng_netflow_copyinfo (:308 INFO) ng_netflow_flow_show (:414 SHOW) ng_netflow_flow_add (:593 rcvdata) ng_netflow_cache_flush (:617 close). netflow.c provably uncompilable: uses FreeBSD-only UMA API (uma_zcreate/uma_zone_set_max/uma_zalloc_arg/uma_zfree_arg/uma_zdestroy) FIB route API (rtalloc1_fib) macros absent from DF (TAILQ_FOREACH_REVERSE_SAFE mtx_trylock mtx_contested). Module wired sys/conf/files:1689-1690 optional netgraph7_netflow option in sys/conf/options:323 but enabling it cannot yield working kernel (linker fails undefined references + netflow.c compile fails earlier). No NETGRAPH7_NETFLOW in any default config. All other vulns in this file unreachable.