terminal: allow copy-paste when selection is scrolled out

We could not paste text when its source went outside the
visible part of the buffer ; this is because we were
incorrectly assuming that our iterator should start at
row 0, while it could very well be negative.

Signed-off-by: Manuel Bachmann <manuel.bachmann@iot.bzh>
Reviewed-by: Bryce Harrington <bryce@osg.samsung.com>

clients/terminal.c

@@ -942,7 +942,7 @@ terminal_send_selection(struct terminal *terminal, int fd)
 		close(fd);
 		return;
 	}
-	for (row = 0; row < terminal->height; row++) {
+	for (row = terminal->selection_start_row; row < terminal->height; row++) {
 		p_row = terminal_get_row(terminal, row);
 		for (col = 0; col < terminal->width; col++) {
 			if (p_row[col].ch == 0x200B) /* space glyph */