[OpenCL] Added a LIT test for ensuring address space mangling is done the same...

[OpenCL] Added a LIT test for ensuring address space mangling is done the same both in OpenCL1.2 and OpenCL2.0.

Patch by Egor Churaev (echuraev).

Reviewers: Anastasia

Subscribers: yaxunl, cfe-commits, bader

Differential Revision: https://reviews.llvm.org/D27403

llvm-svn: 288891