Fix panics related to calling code which expects to be running inside
the NET_EPOCH from outside that epoch.
This leads to panics (with INVARIANTS) such as this one:
panic: Assertion in_epoch(net_epoch_preempt) failed at /usr/src/sys/netinet/if_ether.c:373
cpuid = 7
time = 1586095719
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe0090819700
vpanic() at vpanic+0x182/frame 0xfffffe0090819750
panic() at panic+0x43/frame 0xfffffe00908197b0
arprequest_internal() at arprequest_internal+0x59e/frame 0xfffffe00908198c0
arp_announce_ifaddr() at arp_announce_ifaddr+0x20/frame 0xfffffe00908198e0
carp_master_down_locked() at carp_master_down_locked+0x10d/frame 0xfffffe0090819910
carp_master_down() at carp_master_down+0x79/frame 0xfffffe0090819940
softclock_call_cc() at softclock_call_cc+0x13f/frame 0xfffffe00908199f0
softclock() at softclock+0x7c/frame 0xfffffe0090819a20
ithread_loop() at ithread_loop+0x279/frame 0xfffffe0090819ab0
fork_exit() at fork_exit+0x80/frame 0xfffffe0090819af0
fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe0090819af0
- trap 0, rip = 0, rsp = 0, rbp = 0 ---
Widen the NET_EPOCH to cover the relevant (callback / task) code.