MFC: r240902

MFC: r240902
Attila Bogar reported a bug in mountd when multiple export
entries with different security flavors are in the exports(5)
file. For that case, mountd replies with the security flavors
of the last entry and not the correct one for the client host.
This patch fixes that by storing separate copies of the flavors
for each host/net case, plus a default one for the case where
no hosts/nets are specified on an entry in the exports(5) file.
Unlike the patch in the PR, it replies with the security flavors
for the entry instead of merging the security flavors for all
the entries and replying with that.

git-svn-id: svn://svn.freebsd.org/base/stable/9@241347 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f