fixup??? built-in add -i: start implementing the patch functionality in C

This is necessary as long as `kt/add-i-progress` has not made it into
`maint`.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

add-patch.c

@@ -1362,10 +1362,6 @@ static int patch_update_file(struct add_p_state *s,
 		else
 			prompt_mode_type = PROMPT_HUNK;
 
-		color_fprintf(stdout, s->s.prompt_color,
-			      "(%"PRIuMAX"/%"PRIuMAX") ",
-			      (uintmax_t)hunk_index + 1,
-			      (uintmax_t)file_diff->hunk_nr);
 		color_fprintf(stdout, s->s.prompt_color,
 			      _(s->mode->prompt_mode[prompt_mode_type]),
 			      s->buf.buf);