Avoid byte-swap cache corruption in libdb2

Apply a patch from NetBSD to restore the cached copy of a page to the
machine byte order after a write operation swapped it to the file byte
order.  As a regression test, modify test13 to sync the database file
after each put to exercise this bug.

https://github.com/krb5/krb5/commit/56d02135d4c77b6aa0cb7136477d426248c60a6f
Author: Tom Yu <tlyu@mit.edu>
Commit: 56d02135d4c77b6aa0cb7136477d426248c60a6f
Branch: master
 src/plugins/kdb/db2/libdb2/mpool/mpool.c |    8 ++++++++
 src/plugins/kdb/db2/libdb2/test/run.test |    1 +
 2 files changed, 9 insertions(+), 0 deletions(-)