pcap-linux: fix invalid rcvbuf size

From: Patrick McHardy <kaber@trash.net>

Libpcap issues a SO_RCVBUF when the buffer size if unspecified (zero).
The intention appears to be to set it when its *not* zero.
---

 pcap-linux.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)


diff --git a/pcap-linux.c b/pcap-linux.c
index d9f9f10..d4c06cb 100644
--- a/pcap-linux.c
+++ b/pcap-linux.c
@@ -557,7 +557,7 @@ pcap_activate_linux(pcap_t *handle)
 		goto fail;
 	}
 
-	if (handle->opt.buffer_size == 0) {
+	if (handle->opt.buffer_size != 0) {
 		/*
 		 * Set the socket buffer size to the specified value.
 		 */