Add an Action* member to InputInfo.

Summary:
The CUDA toolchain needs to know which Actions created which InputInfos,
because it needs to attach GPU archs to the various InputInfos.

Reviewers: echristo

Subscribers: jfb, dschuff, jhen, tra, cfe-commits

Differential Revision: http://reviews.llvm.org/D16078

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@257411 91177308-0d34-0410-b5e6-96231b3b80d8