end of file (^D on POSIX-likes) now behaves like q as documented

end of file (^D on POSIX-likes) now behaves like q as documented

This was originally reported againt 5.36.0 where ^D would act
more like 'n' than 'q':

$ ~/perl/v5.36.0-clang14/bin/perl -lde 'print 1; print 2; print 3;'

Loading DB routines from perl5db.pl version 1.73
Editor support available.

Enter h or 'h h' for help, or 'man perldebug' for more help.

main::(-e:1):   print 1; print 2; print 3;
  DB<1> 1
main::(-e:1):   print 1; print 2; print 3;
  DB<1> 2
main::(-e:1):   print 1; print 2; print 3;
  DB<1> 3

(^D at each prompt)

Post 80c1f1e4 this behaved a little differently, since reading ^D
from the stream now sets the eof() flag readline() would return
immediately after each attempt, instead of reading a command.

This produced the same output as above, but only required a single ^D.

But neither of these is correct, both 'q' and ^D are documented to
exit the debugger, and 'q' does that, this changes eof to also
exit the debugger.

Unfortunately the perl5db test infrastructure doesn't support
testing this, and due to the way the debugger interacts with the
terminal, I don't think this is easily tested in core.  I think
a module like Expect or IPC::Run that can interact with a terminal
would be needed.