Initial changes in interfaces of MCAsmStreamer/MCTargetStreamer for
correct debug info emission for Cuda.
- PTX foramt does not support .ascii directives. Added the ability to
- DWARF .file directives must be emitted after .text section and
cannot be inlined in function bodies.
- The initial function label must follow the first debug .loc
directive, not be followed by.
- DWARF sections must be enclosed in braces.