Fix version directive lookup

I don't know how I came up with that pipe but it's certainly wrong.

src/include/mkit.sh

     ver_line=$(
         {
             head -3 "$MKIT_INI"
-            tac "$MKIT_INI" | tail -3
+            tail -3 "$MKIT_INI"
         } | grep -m 1 -E '^# *mkit +version *= *v?[0-9]+\.[0-9]+\.[0-9]+'
     )
     test -n "$ver_line" \