patch 8.1.1801: cannot build without the +eval feature

Problem:    Cannot build without the +eval feature.
Solution:   Always define funcexe_T.

src/version.c

@@ -773,6 +773,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1801,
 /**/
     1800,
 /**/