Close the DWARF line-string stream

[Teylu, Andrew]

Hi,

While building something on top of a GNAT-compiled library, I noticed that 
repeatedly generating symbolic tracebacks led to a memory leak in my program. I 
tracked this down to a missing close in libgnat, which I've attempted to fix 
with the attached patch.

I validated this fix locally with valgrind, as it wasn’t clear to me how to add 
a test for this.

Cheers,

Andrew

0001-ada-Close-the-DWARF-line-string-stream.patch
Description: 0001-ada-Close-the-DWARF-line-string-stream.patch