patch 9.0.0095: conditions are always true

Problem:    Conditions are always true.
Solution:   Remove useless conditions. (closes #10802)
diff --git a/src/buffer.c b/src/buffer.c
index 436c0e9..108d596 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -4297,7 +4297,7 @@
     curitem = 0;
     prevchar_isflag = TRUE;
     prevchar_isitem = FALSE;
-    for (s = usefmt; *s; )
+    for (s = usefmt; *s != NUL; )
     {
 	if (curitem == (int)stl_items_len)
 	{
@@ -4327,7 +4327,7 @@
 	    stl_items_len = new_len;
 	}
 
-	if (*s != NUL && *s != '%')
+	if (*s != '%')
 	    prevchar_isflag = prevchar_isitem = FALSE;
 
 	/*