Consolidate constructormagic macros with Chromium version and remove Chromium override.

Part of work removing dependency on Chromium's base.

Only adds "= delete". From https://codereview.chromium.org/1151443003 :
"This will guarantee the error to be at compile time, and not rely on the call visibility (private)."

In consequence of that change, fixed an illegal copy and removed a bunch of unused variables.

Depends on https://codereview.webrtc.org/1345433002/

BUG=chromium:468375
(in particular comment #37)
NOTRY=true

Review URL: https://codereview.webrtc.org/1342543004

Cr-Commit-Position: refs/heads/master@{#9954}

webrtc/base/socket.h

@@ -26,6 +26,7 @@
 #endif
 
 #include "webrtc/base/basictypes.h"
+#include "webrtc/base/constructormagic.h"
 #include "webrtc/base/socketaddress.h"
 
 // Rather than converting errors into a private namespace,