This patch extends GDB's logging support to the MI.  It's a little messy 
because the MI creates additional ui-file objects (the "consoles") that 
need to have their underlying ui-files changed to either a tee or the 
open log file, depending on redirection mode.  So I added a new 
interpreter proc that hooks into the logging enable/disable, and an 
MI-specific function to change the console's "raw" ui-file.

Although the patch seems straightforward, it entailed quite a bit of 
trial-and-error, and I've probably missed a few cases in the tangled 
tubing that is GDB's ui-file system; comments welcome.  I plan to commit 
this in a few days if no flaws come to light.

Stan
stan@codesourcery.com

2012-06-24  Stan Shebs  <stan@codesourcery.com>

     Make logging work for MI.
     * NEWS: Mention it.
     * interps.h (interp_set_logging_ftype): New typedef.
     (struct interp_procs): New field set_logging_proc.
     (current_interp_set_logging): Declare.
     * interps.c (current_interp_set_logging): New function.
     * cli/cli-logging.c: Include interps.h.
     (set_logging_redirect): Call current_interp_set_logging.
     (pop_output_files): Ditto.
     (handle_redirections): Ditto, plus skip ui-out redirect if MI.
     * mi/mi-console.h (mi_console_set_raw): Declare.
     * mi/mi-console.c (mi_console_set_raw): New function.
     * mi/mi-interp.c (saved_raw_stdout): New global.
     (mi_set_logging): New function.
     (_initialize_mi_interp): Add it to interp procs.

     * gdb.mi/mi-logging.exp: New file.