Revert "Temporarily revert "[DEBUG] Initial adaptation of NVPTX target for debug info emission.""

This reapplies commits: r330271, r330592, r330779.

    [DEBUG] Initial adaptation of NVPTX target for debug info emission.

    Summary:
    Patch adds initial emission of the debug info for NVPTX target.
    Currently, only .file and .loc directives are emitted, everything else is
    commented out to not break the compilation of Cuda.

llvm-svn: 332689