gdb/429: sim/null/ as the default simulator

[ac131313@redhat.com]

>Number:         429
>Category:       gdb
>Synopsis:       sim/null/ as the default simulator
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Sat Mar 16 08:08:03 PST 2002
>Closed-Date:
>Last-Modified:
>Originator:     ac131313@redhat.com
>Release:        unknown-1.0
>Organization:
>Environment:

>Description:
GDB uses configury magic (gdb/config/ISA/*ISA*.mt) to determine if there is a simulator to link against.

Suggest simplifying things so that GDB always links against a simulator.  The sim directory would build a NULL simulator (using sources in sim/null say).
>How-To-Repeat:

>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: