[patch]change dwarf2_start_subfile() to adapt inappropriate dir name

[JuYoung Kim]

> For proper submission of patches to the GDB project, please take a look
> at the file named gdb/CONTRIBUTE.  For the patch, most of us prefer
> unified diffs (use "diff -u" as opposed to "diff -c").

> Last question: Is your mailer capable of keeping the email threading
> information?

You can call me JuYoung. 

I have trouble with the cvs server, because my company's firewall doesn't allow me to connect it.
Instead of me, you or someone can commit this patch, I hope.

My mailer doesn't support the email threading.
Maybe I'll change my email address.

Thanks.