More clean up for Unicode corrigendum #9

Fix some more testcases.

tests/utf8.txt

@@ -62,7 +62,7 @@ VALID
 000007ff
 
 ￿
-NOTUNICODE
+VALID
 0000ffff
 
 <EFBFBD><EFBFBD><EFBFBD><EFBFBD>
@@ -96,7 +96,7 @@ VALID
 0010fffd
 
 􏿿
-NOTUNICODE
+VALID
 0010ffff
 
 <EFBFBD><EFBFBD><EFBFBD><EFBFBD>
@@ -279,16 +279,6 @@ dbff dc00
 NOTUNICODE
 dbff dfff
 
-# Other illegal code positions
-
-￾
-NOTUNICODE
-fffe
-
-￿
-NOTUNICODE
-ffff
-
 ################
 #
 # Some more tests, not from Markus Kuhn's file