patch 8.0.1753: various warnings from a static analyser

Problem:    Various warnings from a static analyser
Solution:   Add type casts, remove unneeded conditions. (Christian Brabandt,
            closes #2770)
diff --git a/src/normal.c b/src/normal.c
index 89b2dc0..84867b5 100644
--- a/src/normal.c
+++ b/src/normal.c
@@ -2610,7 +2610,7 @@
 			end_visual_mode();
 		}
 	    }
-	    else if (c1 < 0)
+	    else
 	    {
 		tabpage_T	*tp;