This reverts merge request !9

Pushing changes to GPU Backend passes (llvm-cbe and DFG2LLVM_NVPTX) fixing handling of loops and some function calls

Compiles correcctly for all targets and target combinations,
pending fix in python script for llvm 4.0 -> llvm 3.4

Bug fix in nvptx and spir backends related to adding arguments to
node functions.

(CPU/GPU/SPIR) based on policy.
Support for scheduling per iteration included.
Further testing required.

Added parsing support for visc in,out,inout attributes. Commit ef703216 in previous llvm 3.4 based repo

The SymVT stuff has not been moved yet, I removed it for now.
The test/VISC tests also have not been moved yet, so they may not
work.