Remove the TUI annotation hack

do_tui_putc has some code to remove annotations from gdb output.  This
was added in 2001, see commit a198b876bbcb.

However, I think this code is not needed.  It seems very unlikely to
enable both annotations and the TUI, and in any case I think this is
something that should not be supported.

So, this patch removes this code.

gdb/ChangeLog
2020-02-22  Tom Tromey  <tom@tromey.com>

	* tui/tui-io.c (do_tui_putc): Don't omit annotations.

Change-Id: I05728110365a362d37c9821df9c8779316100bb8