Problems with memory leak fixes

[Andrew Cagney]

> As Andrew already pointed out, the use of concat in dwarf2.c is incorrect. 
> Worse, the fix is incorrect.  The filename is saved in add_line_info, and
> can not be free'd in decode_line_info; fixing this leak will take more
> careful attention.  Reverting the patch fixes twelve failures in the LD
> testsuite on i686-pc-linux-gnu.
> 
> GDB does not use this code so that doesn't explain which fix broke GDB.

It doesn't get BFD off the hook though either.  Reverting the entire BFD 
part of the change fixes GDB.

Andrew