localedata: Use U+00AF MACRON in more EBCDIC charsets [BZ #27882]

This updates IBM256, IBM277, IBM278, IBM280, IBM284, IBM297, IBM424
in the same way that IBM273 was updated for bug 23290.

IBM256 and IBM424 still have holes after this change, so HAS_HOLES
is not updated.

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>