Hi All,
When using 'target tfile', commands like 'info target' and 'info files'  
don't show the name of the trace file. This patch adds this  
information. It also add a new field in the output of the -trace-status  
command so that frontends can get this inforamtion.

This patch was originally written by Pedro. I have updated and  
regtested it.

Regards,
Abid

Before:
(gdb) info target
Local trace dump file:
Looking at a trace file.
(gdb) interpreter-exec mi -trace-status
^done,supported="file",running="0",stop-reason="request",frames="7215",frames-created="7215",buffer-size="5242880",buffer-free="2833070",disconnected="0",circular="0",user-name="",notes="",start-time="0.000000",stop-time="0.000000"

After:
(gdb) info target
Local trace dump file:
	`/home/abidh/trace.txt'
(gdb) interpreter-exec mi -trace-status
^done,supported="file",trace-file="/home/abidh/trace.txt",running="0",stop-reason="request",frames="7215",frames-created="7215",buffer-size="5242880",buffer-free="2833070",disconnected="0",circular="0",user-name="",notes="",start-time="0.000000",stop-time="0.000000"


2013-02-13  Pedro Alves  <pedro@codesourcery.com>
	    Hafiz Abid Qadeer  <abidh@codesourcery.com>

	gdb/
	* tracepoint.c (trace_status_mi): Output "trace-file" field.
	(tfile_open): Record the trace file's filename in the trace
	status.
	(tfile_files_info): Mention the name of the trace file.
	* tracepoint.h (struct trace_status) <from_file>: Make it hold  
the
	trace file's filename instead of a boolean.

	gdb/doc/
	* gdb.texinfo (GDB/MI Tracepoint Commands) <-trace-status>:
	Document the "trace-file" field.