Fix implicit function declarations.

Change-Id: Ie817cb4df05ae1edb9ec9149a5c15aac5c51dad4
diff --git a/ifaddrs.c b/ifaddrs.c
index 0554ee7..c36fd64 100644
--- a/ifaddrs.c
+++ b/ifaddrs.c
@@ -20,6 +20,7 @@
 #include "ifaddrs.h"
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 #include <sys/types.h>
 #include <dirent.h>
diff --git a/showlease.c b/showlease.c
index 50f96df..1257337 100644
--- a/showlease.c
+++ b/showlease.c
@@ -1,7 +1,9 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <unistd.h>
 
 #include "dhcp.h"
 #include "config.h"