Remove "noerror" parameter from some TUI functions
    
    A few TUI functions take a "noerror" parameter.  This is only checked
    in one spot: in tui_set_source_content, if noerror is false, and if an
    error occurs, then the function will call print_sys_errmsg.
    
    This seems misguided to me, so this patch removes that code and this
    parameter.
    
    gdb/ChangeLog
    2019-08-16  Tom Tromey  <tom@tromey.com>
    
    	* tui/tui-winsource.h (tui_update_source_window)
    	(tui_update_source_window_as_is): Remove "noerror" parameter.
    	* tui/tui-winsource.c (tui_update_source_window)
    	(tui_update_source_window_as_is): Remove "noerror" parameter.
    	(tui_update_source_windows_with_addr)
    	(tui_update_source_windows_with_line)
    	(tui_source_window_base::rerender)
    	(tui_source_window_base::refill): Update.
    	* tui/tui-source.h (tui_set_source_content)
    	(tui_show_symtab_source): Remove "noerror" parameter.
    	* tui/tui-source.c (tui_set_source_content): Remove "noerror"
    	parameter.
    	(tui_show_symtab_source): Likewise.
    	(tui_source_window::maybe_update): Update.
    	* tui/tui-disasm.c (tui_show_disassem)
    	(tui_show_disassem_and_update_source)
    	(tui_disasm_window::do_scroll_vertical)
    	(tui_disasm_window::maybe_update): Update.