Add comments to irt.h about deprecated/disabled IRT interfaces
Add comments to irt.h about deprecated/disabled IRT interfaces

I've included comments about where the interfaces have been used
historically because this is useful for determining when the
interfaces need to be implemented and how they can be tested.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3539
BUG=https://code.google.com/p/nativeclient/issues/detail?id=3484
TEST=none

Review URL: https://codereview.chromium.org/18764004

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@11751 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client