patch 8.0.1660: the terminal API "drop" command doesn't support options

Problem:    The terminal API "drop" command doesn't support options.
Solution:   Implement the options.
diff --git a/src/misc2.c b/src/misc2.c
index cd1dcf0..9127e66 100644
--- a/src/misc2.c
+++ b/src/misc2.c
@@ -3161,7 +3161,7 @@
     int		c;
 
     if (eap != NULL && eap->force_ff != 0)
-	c = eap->cmd[eap->force_ff];
+	c = eap->force_ff;
     else
     {
 	if ((eap != NULL && eap->force_bin != 0)