passt: Fix build with gcc 7, use std=c99, enable some more Clang checkers

Unions and structs, you all have names now.

Take the chance to enable bugprone-reserved-identifier,
cert-dcl37-c, and cert-dcl51-cpp checkers in clang-tidy.

Provide a ffsl() weak declaration using gcc built-in.

Start reordering includes, but that's not enough for the
llvm-include-order checker yet.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/pcap.c b/pcap.c
index 8ff1636..2c390f2 100644
--- a/pcap.c
+++ b/pcap.c
@@ -12,7 +12,6 @@
  * Author: Stefano Brivio <sbrivio@redhat.com>
  */
 
-#define _GNU_SOURCE
 #include <stdio.h>
 #include <stddef.h>
 #include <stdint.h>
@@ -29,6 +28,8 @@
 #include <unistd.h>
 #include <net/if.h>
 
+#include <linux/ipv6.h>
+
 #include "util.h"
 #include "passt.h"