This patch adds the `nocallback` attribute to the NVVM intrinsics that
did not use the `DefaultAttrsIntrinsic` method that includes it already.
The `nocallback` attribute states that the intrinsic function cannot
enter back into the caller's translation-unit. This allows as to
determine that a function calling a `nocallback` function can have the
`norecurse` attribute. This should be safe for all the NVVM intrinsics
because they do not call other functions within the translation unit.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D125937
dbffa4073c