Support mouse clicks on tab bar on TTY frames

Support mouse clicks on tab bar on TTY frames

This for now doesn't work on GPM.
* src/xdisp.c (display_tab_bar): Make the loop over tab-bar
items more efficient.
(tab_bar_item_info, tool_bar_item_info): Correct data type for
CHARPOS.
(tty_get_tab_bar_item, tty_handle_tab_bar_click): New functions.
(note_mouse_highlight): Handle help-echo of tab-bar tabs on
TTY frames.
* src/w32inevt.c (do_mouse_event): Call
tty_handle_tab_bar_click to process mouse clicks on the tab bar.
* src/termchar.h (tty_handle_tab_bar_click): Add prototype.
* src/w32console.c (w32con_set_terminal_modes): Disable Quick
Edit mode on entry, to make sure mouse events get reported to
us.