gdb/

gdb/
	Redirect also uiout and stdtarg{,err} in execute_command_to_string.
	* cli-logging.c (struct saved_output_files) <targerr>: New.
	(set_logging_redirect, pop_output_files, handle_redirections):
	Redirect also gdb_stdtargerr.
	* defs.h (struct ui_out, make_cleanup_ui_out_redirect_pop): New
	declarations.
	* event-top.c (gdb_setup_readline, gdb_disable_readline): Redirect
	also gdb_stdtargerr.
	* top.c (execute_command_to_string): Move make_cleanup_ui_file_delete
	to the top.  Redirect also gdb_stdlog, gdb_stdtarg and gdb_stdtargerr.
	Use ui_out_redirect, register make_cleanup_ui_out_redirect_pop.
	* tui/tui-io.c (tui_setup_io): Redirect also gdb_stdtargerr.
	* utils.c (do_ui_out_redirect_pop, make_cleanup_ui_out_redirect_pop):
	New functions.

gdb/testsuite/
	* gdb.python/python.exp (set height 0, collect help from uiout)
	(verify help to uiout): New tests.