P2p checkpoint.

- set USE_PEER_TO_PEER=3 (requires HCC "am_memtracker_update_peers")
- when enabling peer, turn it on for previously allocated memory.
- hipDeviceCanAccessPeer is no longer self-ware (self does not qualify
  as a peer)
- device peerlist always includes self, so when we call allow_access
  we never remove self access.
- hipDeviceReset() removes old peer mappings.

samples/1_Utils/hipInfo/hipInfo.cpp

@@ -127,7 +127,7 @@ void printDeviceProp (int deviceId)
     for (int i=0; i<deviceCnt; i++) {
         int isPeer;
         hipDeviceCanAccessPeer(&isPeer, deviceId, i);
-        if ((i != deviceId) && isPeer) {
+        if (isPeer) {
             cout << "device#" << i << " ";
         }
     }