patch 8.0.0965: not restoring cursor shape after it was set in a terminal

Problem:    The cursor shape is not reset after it was changed in a terminal.
Solution:   Request the original cursor shape and restore it.  Add t_RS.
            Do not add t_SH for now, it does not work properly.
diff --git a/src/option.c b/src/option.c
index 0bcf216..a651497 100644
--- a/src/option.c
+++ b/src/option.c
@@ -3179,6 +3179,7 @@
     p_term("t_SC", T_CSC)
     p_term("t_EC", T_CEC)
     p_term("t_SH", T_CSH)
+    p_term("t_RS", T_CRS)
     p_term("t_IS", T_CIS)
     p_term("t_ke", T_KE)
     p_term("t_ks", T_KS)