[Polly][GPUJIT] Fixed OpenCL 2.0 min requirement for Error codes

Summary: Removed OpenCL error code identifiers introduced in version 2.0.

Reviewers: grosser, bollu

Reviewed By: bollu

Subscribers: yaxunl, Anastasia, pollydev, llvm-commits

Tags: #polly

Differential Revision: https://reviews.llvm.org/D32962

llvm-svn: 302423