Add missing <malloc.h> and <string.h> includes.

Change-Id: Ia41756e607663d056e7d2fdd7ecbec7e5841a913
diff --git a/toolbox/renice.c b/toolbox/renice.c
index 9dfeb51..99a06f4 100644
--- a/toolbox/renice.c
+++ b/toolbox/renice.c
@@ -32,6 +32,7 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <stdlib.h>
+#include <string.h>
 #include <sys/time.h>
 #include <sys/resource.h>
 #include <sched.h>