Convert dw2-case-insensitive.exp to DWARF assembler

I used contrib/dwarf-to-dwarf-assembler.py to convert
dw2-case-insensitive.exp to use the DWARF assembler.  The output
needed some minor changes to fully work, but not really all that much.
The .c file also needed a small change, and I went ahead and removed
other extraneous code.

Approved-by: Kevin Buettner <kevinb@redhat.com>