reuseport_select.o is not cleaned or rebuilt

[Jiang1155]

I made some changes to reuseport_select.c and run go build/go run server.go primary. But the change does not take effect. After some debugging, I noticed that go build or go clean command does not check bpf/reuseport_select.o. It is still the old one.

I have to manually delete bpf/reuseport_select.o and run "bpf/reuseport_select.o" again to make new ebpf program take effects. It will be nice to fix this.

btw, if you want to use printk() from lib/dbg.h, you will see some compiler errors (because it took from cilium but not all of them). I tried to fix one or two errors but it seems a lot. I finally just copy the printk() macro from dbg.h to the reuseport_select.c. lol