Support for "break *ADDRESS thread THREADNO"

[Eli Zaretskii]

> Date: Tue, 12 Apr 2005 14:55:49 -0400
> From: Daniel Jacobowitz <drow@false.org>
> Cc: "Maciej W. Rozycki" <macro@mips.com>, gdb-patches@sources.redhat.com
> 
> There's already common code for this, that's where most of the 'thread
> THREADNO' support is.  I think it's in linespec.c somewhere, but it
> might be in breakpoint.c.

Doing this in one of these two place would be okay, since they are
language independent.

> TBH, the mechanism is fragile; I can't think of a more robust way but
> there must be one.

How about a convenience variable $thread that will hold the current
thread ID?  Then we could simply use a condition "if $thread == TID".

Or maybe a command option "break --thread=ID *ADDR".  (Or did we
decide to not use such syntax?)