stdint should not be imported into OpenCL kernels

Key change : OpenCL doesn't need the same type information to be included in kernels (in particular, including files *at all* is somewhat deprecated : http://devgurus.amd.com/message/1296050)

This PR should cure the failure of the opencl test script shown on http://deeplearning.net/software/theano/tutorial/using_gpu.html

The code has been before/after tested on my Linux OpenCL system (with an Nvidia graphics card, but no CUDA libraries installed).  For non-OpenCL systems, the gpuarray output should be unchanged.

The PR also solves the central issue behind "Theano fails when device=opencl #2189" (where the bug is correctly identified, and a PR is asked for, but the issue was closed because it wasn't clear that libgpuarray hadn't been 'messed with').

Also this should fix:
"stdint.h not found error on MacOS Mavericks when running theano test on OpenCL using libgpuarray" found at https://groups.google.com/forum/#!topic/theano-users/4HrFKsL5c2w

If this is acceptable, I'd be happy to continue ploughing ahead with OpenCL/gpuarray fixes (since, FWIW, OpenCL is more appealing to this Linux user than CUDA...)