patch 8.0.0723: arglist test fails if file name case is ignored

Problem:    Arglist test fails if file name case is ignored.
Solution:   Wipe existing buffers, check for fname_case property.

src/version.c

@@ -769,6 +769,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    723,
 /**/
     722,
 /**/