-1. Print variables from the core file (data and stack), and text
-(from the exec file). This tests whether the corefile sections are
-mapped to the right addresses.
-2. Test what happens when we get a new exec file without explicitly
-getting rid of the core file (we at least must avoid core dumps and such).
-3. Test backtrace in corefile.exp.
-4. Test ability to run program when there is a core target, then go