NVPTX: Don't insert an extra empty line at the end of the last section.

NVPTX: Don't insert an extra empty line at the end of the last section.

This was arbitrarily appearing in only the last section emitted - which
made tests more sensitive than they needed to be (removing the last
section - like the macinfo section change that's coming after this)
would, surprisingly, move the blank line to the previous section.