Mark the masterfile-format type 'map' as deprecated

Mark the masterfile-format type 'map' as deprecated

The map masterfile-format is very fragile and it needs API bump every
time a RBTDB data structures changes.  Also while testing it, we found
out that files larger than 2GB weren't loading and nobody noticed, and
loading many map files were also failing (subject to kernel limits).

Thus we are marking the masterfile-format type 'map' as deprecated and
to be removed in the next stable BIND 9 release.

(cherry picked from commit 6b7a488cbcedf0fcb3f9de3e8e63795afd599781)