Update precompiled pdfium for mac to chromium/3071 and add version info file with minimal build instructions

common/check_new_version.h

@@ -0,0 +1,26 @@
+#ifndef __CHECKUPDATE_H
+#define __CHECKUPDATE_H
+
+#include "http_worker.h"
+#include "yacreader_global.h"
+
+#include <QByteArray>
+#include <QThread>
+
+ class HttpVersionChecker : public HttpWorker
+ {
+		 Q_OBJECT
+	public:
+		HttpVersionChecker();
+	public slots:
+
+	private:
+		bool found;
+	private slots:
+		bool checkNewVersion(QString sourceContent);
+		void checkNewVersion(const QByteArray & data);
+	signals:
+		void newVersionDetected();
+ };
+
+#endif