Add RTC_ prefix to contructormagic macros.

We must remove dependency on Chromium, i.e. we can't use Chromium's base/logging.h. That means we need to define these macros in WebRTC also when doing Chromium builds. And this causes redefinition.

* DISALLOW_ASSIGN -> RTC_DISALLOW_ASSIGN
* DISALLOW_COPY_AND_ASSIGN -> RTC_DISALLOW_COPY_AND_ASSIGN
* DISALLOW_IMPLICIT_CONSTRUCTORS -> RTC_DISALLOW_IMPLICIT_CONSTRUCTORS

Related CL: https://codereview.webrtc.org/1335923002/

BUG=chromium:468375
NOTRY=true

Review URL: https://codereview.webrtc.org/1345433002

Cr-Commit-Position: refs/heads/master@{#9953}

webrtc/modules/audio_coding/neteq/tools/packet.h

@@ -114,7 +114,7 @@ class Packet {
   double time_ms_;     // Used to denote a packet's arrival time.
   bool valid_header_;  // Set by the RtpHeaderParser.
 
-  DISALLOW_COPY_AND_ASSIGN(Packet);
+  RTC_DISALLOW_COPY_AND_ASSIGN(Packet);
 };
 
 }  // namespace test