Add -b/-l options to localedef(1) to specify output endianness and use
it appropriately when building share/ctypedef and share/colldef.

This makes the resulting locale data in EL->EB (amd64->powerpc64) cross
build and in the native EB build match. Revert the changes done to libc
in r308170 as they are no longer needed.

PR: 231965
Reviewed by: bapt, emaste, sbruno, 0mp
Approved by: kib (mentor)
Differential Revision: https://reviews.freebsd.org/D17603