Fix test cases/frameworks/19 pcap for OSX

test cases/frameworks/19 pcap/pcap_prog.c

@@ -4,6 +4,12 @@ int
 main()
 {
     char errbuf[PCAP_ERRBUF_SIZE];
-    pcap_t *p = pcap_create(NULL, errbuf);
+#ifdef __APPLE__
+    // source = NULL for "any" doesn't work on macOS (linux only?)
+    char *source = "en0";
+#else
+    char *source = NULL;
+#endif
+    pcap_t *p = pcap_create(source, errbuf);
     return p == NULL;
 }