patch 8.2.3388: fnamemodify('path/..', ':p') differs from using 'path/../'

Problem:    fnamemodify('path/..', ':p') differs from using 'path/../'.
Solution:   Include the "/.." in the directory name. (closes #8808)

src/version.c

@@ -755,6 +755,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3388,
 /**/
     3387,
 /**/