clearly mark unused error messages as such

sql/share/errmsg-utf8.txt

@@ -5966,12 +5966,10 @@ ER_EVENT_NEITHER_M_EXPR_NOR_M_AT
         ger "Kein DATETIME-Ausdruck angegeben"
 
 ER_UNUSED_2
-        eng "Column count of mysql.%s is wrong. Expected %d, found %d. The table is probably corrupted"
-        ger "Spaltenanzahl von mysql.%s falsch. %d erwartet, aber %d gefunden. Tabelle ist wahrscheinlich beschädigt"
+        eng ""
 
 ER_UNUSED_3
-        eng "Cannot load from mysql.%s. The table is probably corrupted"
-        ger "Kann mysql.%s nicht einlesen. Tabelle ist wahrscheinlich beschädigt"
+        eng ""
 ER_EVENT_CANNOT_DELETE
         eng "Failed to delete the event from mysql.event"
         ger "Löschen des Events aus mysql.event fehlgeschlagen"
@@ -5999,8 +5997,7 @@ ER_CANT_LOCK_LOG_TABLE
         eng "You can't use locks with log tables."
         ger "Log-Tabellen können nicht gesperrt werden."
 ER_UNUSED_4
-        eng "Upholding foreign key constraints for table '%.192s', entry '%-.192s', key %d would lead to a duplicate entry"
-        ger "Aufrechterhalten der Fremdschlüssel-Beschränkungen für Tabelle '%.192s', Eintrag '%-.192s', Schlüssel %d würde zu einem doppelten Eintrag führen"
+        eng ""
 ER_COL_COUNT_DOESNT_MATCH_PLEASE_UPDATE
         eng "Column count of mysql.%s is wrong. Expected %d, found %d. Created with MariaDB %d, now running %d. Please use mysql_upgrade to fix this error."
         ger "Spaltenanzahl von mysql.%s falsch. %d erwartet, aber %d erhalten. Erzeugt mit MariaDB %d, jetzt unter %d. Bitte benutzen Sie mysql_upgrade, um den Fehler zu beheben"
@@ -6180,9 +6177,8 @@ ER_TRG_CANT_OPEN_TABLE
 ER_CANT_CREATE_SROUTINE
   eng "Cannot create stored routine `%-.64s`. Check warnings"
   ger "Kann gespeicherte Routine `%-.64s` nicht erzeugen. Beachten Sie die Warnungen"
-ER_NEVER_USED
-  eng "Ambiguous slave modes combination. %s"
-  ger "Mehrdeutige Kombination von Slave-Modi. %s"
+ER_UNUSED
+  eng ""
 ER_NO_FORMAT_DESCRIPTION_EVENT_BEFORE_BINLOG_STATEMENT
   eng "The BINLOG statement of type `%s` was not preceded by a format description BINLOG statement."
   ger "Der BINLOG-Anweisung vom Typ `%s` ging keine BINLOG-Anweisung zur Formatbeschreibung voran."
@@ -6620,28 +6616,8 @@ ER_ROW_DOES_NOT_MATCH_GIVEN_PARTITION_SET
   eng "Found a row not matching the given partition set"
   swe "Hittade en rad som inte passar i någon given partition"
 
-# Not used any longer, use ER_UNKNOWN_PARTITION which includes the tablename.
-# was ER_NO_SUCH_PARTITION
-ER_NO_SUCH_PARTITION__UNUSED
-  cze "partion '%-.64s' neexistuje"
-  dan "partition '%-.64s' eksisterer ikke"
-  nla "partition '%-.64s' bestaat niet"
-  eng "partition '%-.64s' doesn't exist"
-  est "partition '%-.64s' ei eksisteeri"
-  fre "La partition '%-.64s' n'existe pas"
-  ger "Die partition '%-.64s' existiert nicht"
-  hun "A '%-.64s' partition nem letezik"
-  ita "La tabella particione '%-.64s' non esiste"
-  jpn "パーティション '%-.64s' は存在しません。"
-  nor "Partition '%-.64s' doesn't exist"
-  norwegian-ny "Partition '%-.64s' doesn't exist"
-  pol "Partition '%-.64s' doesn't exist"
-  por "Particion '%-.64s' n<>o existe"
-  rum "Partition '%-.64s' nu exista"
-  serbian "Partition '%-.64s' ne postoji"
-  slo "Partition '%-.64s' doesn't exist"
-  spa "Particion '%-.64s' no existe"
-  swe "Det finns ingen partition som heter '%-.64s'"
+ER_UNUSED_5
+  eng ""
 
 ER_CHANGE_RPL_INFO_REPOSITORY_FAILURE
   eng "Failure while changing the type of replication repository: %s."
@@ -7049,12 +7025,12 @@ ER_UNKNOWN_OPTION
   eng "Unknown option '%-.64s'"
 ER_BAD_OPTION_VALUE
   eng "Incorrect value '%-.64s' for option '%-.64s'"
-ER_NOT_USED_ERROR_MESSAGE
+ER_UNUSED_6
   eng ""
-ER_NOT_USED_ERROR_MESSAGE2
+ER_UNUSED_7
+  eng ""
+ER_UNUSED_8
   eng ""
-ER_CANT_DO_ONLINE
-        eng "Can't execute the given '%s' command as online"
 ER_DATA_OVERFLOW 22003
         eng "Got overflow when converting '%-.128s' to %-.32s. Value truncated."
 ER_DATA_TRUNCATED 22003