Summary:
This lets you build with one CUDA installation but use ptxas from
another install.
This is useful e.g. if you want to avoid bugs in an old ptxas without
actually upgrading wholesale to a newer CUDA version.
Reviewers: tra
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D27788
llvm-svn: 289847
Justin Lebar