Coding bug in insert-file-contents-internal

[Ben Wing]

> This is a completely tentative patch, bceause I'm still not 
> quite clear on the interactions of bindings, GCPRO, 
> unwind-protect and the like in the C layer. I *think* it's 
> pointless to specbind() DEFVAR_LISPed variables, because it 
> seems to me that this would break the magic link between the 
> C variable and the Lisp symbol --- the magic forwarding 
> symbol would wind up on the specbinding stack --- and the C 
> code uses the variable...  so I've tried to 
> record_unwind_protect it instead. I'm not quite sure if I've 
> done it right, or if I need to GCPRO something (I don't think 
> so: stuff on the specbinding stack and stuff in DEFVAR_LISPed 
> variables are both found by the garbage collector anyway,
> right?)  record_unwind_protect()?)
> 
> 
> It compiles, I don't know if it runs, I don't know if it's 
> safe

Yes.

> I don't know if there's a better way to do it:

Yes.

record_unwind_protect() and specbind() (of a Q... Symbol that names the
variable) are both fine.  Easiest/best is internal_bind_lisp_object().