RFA: don't read coff line number unless we have symbols too

[Jim Blandy]

Joel Brobecker <brobecker@gnat.com> writes:
> Hello,
> > Seems OK to me.
> 
> This change seems to be causing some problems. Unfortunately, I don't
> have all the details yet. Can we put this patch on hold until I collect
> all the information, please?

Sure.

It's supposed to be semantically undetectable, except for not reading
the line number info.  The code simply makes GDB not read info from
the executable that it will never use.  If that expectation is
incorrect, I definitely want to know.