Support setcpuaffinity on linux/bsd

Currently, there are several types of threads/child processes of a
redis server. Sometimes we need deeply optimise the performance of
redis, so we would like to isolate threads/processes.

There were some discussion about cpu affinity cases in the issue:
https://github.com/antirez/redis/issues/2863

So implement cpu affinity setting by redis.conf in this patch, then
we can config server_cpulist/bio_cpulist/aof_rewrite_cpulist/
bgsave_cpulist by cpu list.

Examples of cpulist in redis.conf:
server_cpulist 0-7:2      means cpu affinity 0,2,4,6
bio_cpulist 1,3           means cpu affinity 1,3
aof_rewrite_cpulist 8-11  means cpu affinity 8,9,10,11
bgsave_cpulist 1,10-11    means cpu affinity 1,10,11

Test on linux/freebsd, both work fine.

Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
