src: add process.binding('config')

It turns out that userland likes to override process.config with
their own stuff. If we want to be able to depend on it in any way,
we need our own internal mechanism.

This adds a new private process.binding('config') that is
intended to serve as a container for internal flags and compile
time configs that need to be passed on to the JS layer.

PR-URL: #6266
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

node.gyp

@@ -124,6 +124,7 @@
         'src/js_stream.cc',
         'src/node.cc',
         'src/node_buffer.cc',
+        'src/node_config.cc',
         'src/node_constants.cc',
         'src/node_contextify.cc',
         'src/node_file.cc',

src/node_config.cc

@@ -0,0 +1,36 @@
+#include "node.h"
+#include "env.h"
+#include "env-inl.h"
+#include "util.h"
+#include "util-inl.h"
+
+
+namespace node {
+
+using v8::Context;
+using v8::Local;
+using v8::Object;
+using v8::Value;
+using v8::ReadOnly;
+
+// The config binding is used to provide an internal view of compile or runtime
+// config options that are required internally by lib/*.js code. This is an
+// alternative to dropping additional properties onto the process object as
+// has been the practice previously in node.cc.
+
+#define READONLY_BOOLEAN_PROPERTY(str)                                        \
+  do {                                                                        \
+    target->DefineOwnProperty(env->context(),                                 \
+                              OneByteString(env->isolate(), str),             \
+                              True(env->isolate()), ReadOnly).FromJust();     \
+  } while (0)
+
+void InitConfig(Local<Object> target,
+                Local<Value> unused,
+                Local<Context> context) {
+  // Environment* env = Environment::GetCurrent(context);
+}
+
+}  // namespace node
+
+NODE_MODULE_CONTEXT_AWARE_BUILTIN(config, node::InitConfig)