socket: define IP_FREEBIND if not defined

src/missing.h

@@ -26,6 +26,7 @@
 
 #include <sys/resource.h>
 #include <sys/syscall.h>
+#include <fcntl.h>
 
 #ifndef RLIMIT_RTTIME
 #define RLIMIT_RTTIME 15
@@ -43,6 +44,10 @@
 #define F_GETPIPE_SZ (F_LINUX_SPECIFIC_BASE + 8)
 #endif
 
+#ifndef IP_FREEBIND
+#define IP_FREEBIND 15
+#endif
+
 static inline int pivot_root(const char *new_root, const char *put_old) {
         return syscall(SYS_pivot_root, new_root, put_old);
 }

src/socket-util.c

@@ -33,6 +33,7 @@
 #include "macro.h"
 #include "util.h"
 #include "socket-util.h"
+#include "missing.h"
 
 int socket_address_parse(SocketAddress *a, const char *s) {
         int r;