patch 8.1.0648: custom operators can't act upon a forced motion

Problem:    Custom operators can't act upon a forced motion. (Christian
            Wellenbrock)
Solution:   Add the forced motion to the mode() result. (Christian Brabandt,
            closes #3490)
diff --git a/src/evalfunc.c b/src/evalfunc.c
index a29f0ff..d94bf8d 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -8506,7 +8506,11 @@
     {
 	buf[0] = 'n';
 	if (finish_op)
+	{
 	    buf[1] = 'o';
+	    // to be able to detect force-linewise/blockwise/characterwise operations
+	    buf[2] = motion_force;
+	}
 	else if (restart_edit == 'I' || restart_edit == 'R'
 							|| restart_edit == 'V')
 	{