Fix package priority index in pg_dump_sort

The priority table mistakenly indexed the package entry with
PRIO_PACKAGE instead of DO_PACKAGE key. Under Clang, that collides with
another designated initializer and overwrites a later entry.

Warning excerpt:

```
pg_dump_sort.c:117:23: warning: initializer overrides prior
initialization of this subobject [-Winitializer-overrides]
```

Author: c2main

src/bin/pg_dump/pg_dump_sort.c

@@ -110,7 +110,7 @@ static const int dbObjectTypePriority[] =
 	[DO_EXTENSION] = PRIO_EXTENSION,
 	[DO_TYPE] = PRIO_TYPE,
 	[DO_SHELL_TYPE] = PRIO_TYPE,
-	[PRIO_PACKAGE] = PRIO_PACKAGE,
+	[DO_PACKAGE] = PRIO_PACKAGE,
 	[DO_FUNC] = PRIO_FUNC,
 	[DO_AGG] = PRIO_AGG,
 	[DO_OPERATOR] = PRIO_OPERATOR,