Merge pull request #358 from dwrensha/getenv-osx

include stdlib.h to fix build on OSX

c++/src/capnp/compiler/node-translator.c++

@@ -26,6 +26,7 @@
 #include <kj/arena.h>
 #include <set>
 #include <map>
+#include <stdlib.h>
 
 namespace capnp {
 namespace compiler {