patch 8.2.2776: :mksession uses current value of 'splitbelow' and 'splitright'

Problem:    :mksession uses current value of 'splitbelow' and 'splitright'
            even though "options" is not in 'sessionoptions'. (Maxim Kim)
Solution:   Save and restore the values, instead of setting to the current
            value. (closes #8119)

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2776,
 /**/
     2775,
 /**/