patch 8.2.4209: partial in 'opfunc' cannot use an imported function

Problem:    partial in 'opfunc' cannot use an imported function.
Solution:   Also expand the function name in a partial. (closes #9614)

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4209,
 /**/
     4208,
 /**/