Move server_t from resolv.h to netio.h

src/utils/common/exec.c

src/utils/common/netio.c

src/utils/common/netio.h

src/utils/common/params.c

src/utils/common/params.h

src/utils/common/resolv.c

src/utils/common/resolv.h

src/utils/nsupdate/nsupdate_exec.c

src/utils/nsupdate/nsupdate_params.c

src/utils/nsupdate/nsupdate_params.h