Generate version header when configuring project

The basic idea is we create a version header template at
"src/base/version.h.in" and the build systems are expected to replace
strings that are enclosed with @ symbols and generate
"src/base/version.h" for other source files to consume/include.

src/base/net/dnsupdater.cpp

@@ -34,6 +34,7 @@
 
 #include "base/logger.h"
 #include "base/net/downloadmanager.h"
+#include "base/version.h"
 
 using namespace Net;