Deal with yet another issue related to "Norwegian (Bokmål)" locale.

Deal with yet another issue related to "Norwegian (Bokmål)" locale.

It emerges that recent versions of Windows (at least 2016 Standard)
spell this locale name as "Norwegian Bokmål_Norway.1252", defeating
our mapping code that translates "Norwegian (Bokmål)_Norway" to
something that's all-ASCII (cf commits db29620d4 and aa1d2fc5e).
Add another mapping entry to handle this spelling.

Per bug #16068 from Robert Ford.  Like the previous patches,
back-patch to all supported branches.

Discussion: http://postgr.es/m/16068-4cb6eeaa7eb46d93@postgresql.org