Squelch an unused parameter warning.

When libpcap was compiled without the remote capture support, compiling
tcpdump would emit the following warning:

./tcpdump.c: In function ‘find_interface_by_number’:
./tcpdump.c:1122:38: warning: unused parameter ‘url’ [-Wunused-parameter]
 find_interface_by_number(const char *url, long devnum)
                                      ^~~

Add a conditional "unused" attribute to manage that.

[skip ci]

1 files changed, 5 insertions, 1 deletions

diff --git a/tcpdump.c b/tcpdump.c
index 8ea49251..b900a422 100644
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -1119,7 +1119,11 @@ parse_interface_number(const char *device)
 }
 
 static char *
-find_interface_by_number(const char *url, long devnum)
+find_interface_by_number(const char *url
+#ifndef HAVE_PCAP_FINDALLDEVS_EX
+_U_
+#endif
+, long devnum)
 {
 	pcap_if_t *dev, *devlist;
 	long i;