This matches the way nvcc encapsulates GPU binaries into host object file.
Now cuobjdump can deal with clang-compiled object files.

Differential Revision: https://reviews.llvm.org/D23429

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@278549 91177308-0d34-0410-b5e6-96231b3b80d8