[RFA/dwarf2] Small problem scanning line table for included files

[Michael Chastain]

Now that I look, I see this happening in my test bed, too.
gdb HEAD suite HEAD -gdwarf-2 has PASS with gcc 3.3.4 and
FAIL with gcc 3.4.1.

I had better take another look at my gcc 3.3.4 versus gcc 3.4.1
tables and see if I overlooked anything else in there!

  http://www.shout.net/~mec/sunday/current/Compare-by-gcc-334-341.html

The regressions I know about are:

  gcc 3.4.1 versus gcc 3.3.4
    gcc/12267 gcc/13708 gcc/13956
    gdb/1537 gdb/1540

Michael C