fix: --count exists without waiting for extra input message

[regalk13]

Fixes issue of --count

Prev:

--count=1
...
nmsg_io: iothr=0x5586bf6c3590 count_nmsg_payload_in=2
nmsgtool: totals: payloads_in 2 payloads_out 1 container_recvs 1 container_drops 0

Now:

--count=1
...
nmsg_io: iothr=0x5634f5432590 count_nmsg_payload_in=1
nmsgtool: totals: payloads_in 1 payloads_out 1 container_recvs 1 container_drops 0

Tested with -r flag with nmsg files and json inputs.