decode: fix pointers and fix null into string

Fixes bug #1133337.

R=jameinel
CC=
https://codereview.appspot.com/8019043

.lbox.check

diff --git a/.lbox.check b/.lbox.check
new file mode 100755
index 0000000..b4211c2
--- /dev/null
+++ b/.lbox.check
@@ -0,0 +1,20 @@
+#!/bin/sh
+
+set -e
+
+BADFMT=`find * -name '*.go' | xargs gofmt -l`
+if [ -n "$BADFMT" ]; then
+	BADFMT=`echo "$BADFMT" | sed "s/^/  /"`
+	echo -e "gofmt is sad:\n\n$BADFMT"
+	exit 1
+fi
+
+VERSION=`go version | awk '{print $3}'`
+if [ $VERSION == 'devel' ]; then
+	go tool vet \
+		-methods \
+		-printf \
+		-rangeloops \
+		-printfuncs 'ErrorContextf:1,notFoundf:0,badReqErrorf:0,Commitf:0,Snapshotf:0,Debugf:0' \
+		.
+fi

decode.go

diff --git a/decode.go b/decode.go
index f4a8f2c..b03f36e 100644
--- a/decode.go
+++ b/decode.go
@@ -1,6 +1,7 @@
 package goyaml
 
 // #cgo LDFLAGS: -lm -lpthread
+// #cgo windows CFLAGS: -DYAML_DECLARE_STATIC=1 -Dstrdup=_strdup
 // #cgo CFLAGS: -I. -DHAVE_CONFIG_H=1
 //
 // #include "helpers.h"