* gdbtk.c (gdbtk_wait gdbtk_init): Use different method of

	* gdbtk.c (gdbtk_wait gdbtk_init):  Use different method of
	enabling I/O interrupts for SVR4 (streams).
	* (start_saving_output save_output get_saved_output
	finish_saving_output flush_holdbuf gdbtk_flush gdbtk_fputs
	gdbtk_init):
	Totally revamp to use TCLs dynamic string functions.  Also, quote
	all data passed back to TCL to prevent errors with unmatched
	braces, odd characters, etc...  This fixes several wierd problems
	with outputting strings containing unmatched braces.
	* (breakpoint_notify gdb_loc):  Use long hex format to output
	addresses of breakpoints and PCs.  This fixes some Alpha problems.
	* (breakpoint_notify):  Add stream arg to call to gdbtk_fputs.
	* (gdb_listfiles):  Also, go through the symtabs when looking for
	files.  This makes xcoff work (sort of), but probably breaks
	something else.
	* (gdb_stop):  Return TCL_OK instead of nothing.  This fixes odd
	TCL errors when hitting stop button.
	* (tk_command):  Don't pass interp->result on to Tcl_{Var}Eval, as
	that will trash the result.  strdup the result instead and pass
	that on.  Improve error handling as well.

	* gdbtk.tcl (gdbtk_tcl_flush):  Use global def of
	current_output_win.  Makes flushing actually work!
	* (asm_win_name create_asm_win update_assembly):  Bunch of fixes
	to make assembly windows stop flashing when loading a new file.
	* (gdbtk_tcl_busy gdbtk_tcl_idle):  Use catch to prevent gdb_cmd
	errors from losing control.
	* (create_source_window):  Add source file selection to View menu.
	* (create_command_window (<Key-Return> binding):  Quote text fed
	into gdb_cmd to prevent eval errors.