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

llvm-svn: 257411