Add missing <stdlib.h> to streams.cc
diff --git a/enc/streams.cc b/enc/streams.cc
index c5a9824..edb17c3 100644
--- a/enc/streams.cc
+++ b/enc/streams.cc
@@ -18,6 +18,7 @@
 #include "./streams.h"
 
 #include <assert.h>
+#include <stdlib.h>
 #include <string.h>
 
 namespace brotli {