client: Additional counters for the statistics

Add more counters and start counting them when reading from the
PCAP library and when trying to write to the socket.

Change-Id: I52d3064a265b402ac849d8578a14f718156c0805
diff --git a/src/osmo_client_main.c b/src/osmo_client_main.c
index 945a871..0b53939 100644
--- a/src/osmo_client_main.c
+++ b/src/osmo_client_main.c
@@ -60,6 +60,8 @@
 	[CLIENT_CTR_2BIG]		= { "bpf.too_big",		"Captured data too big " },
 	[CLIENT_CTR_NOMEM]		= { "client.no_mem",		"No memory available   " },
 	[CLIENT_CTR_QERR]		= { "client.queue_err",		"Can not queue data    " },
+	[CLIENT_CTR_PERR]		= { "client.pcap_err",		"libpcap error         " },
+	[CLIENT_CTR_WERR]		= { "client.write_err",		"Write error           " },
 };
 
 static const struct rate_ctr_group_desc pcap_client_ctr_group_desc = {