An old tables implementation had all tables preallocated,
so when user did ipfw table N flush it always worked, but now
when table N doesn't exist the kernel returns ESRCH error.
This isn't fatal error for flush and destroy commands. Do not
call err(3) when errno is equal to ESRCH. Also warn only when
quiet mode isn't enabled. This fixes a regression in behavior,
when old rules are loaded from file.
Also use correct value for switch in the table_swap().

Reported by: Kevin Oberman
MFC after: 3 days