Pull up following revision(s) (requested by sevan in ticket #810):

crypto/external/bsd/netpgp/dist/src/libbn/libnetpgpbn.3: revision 1.5
crypto/external/bsd/netpgp/dist/src/libbn/libnetpgpbn.3: revision 1.6
crypto/external/bsd/netpgp/dist/src/libmj/libmj.3: revision 1.8
crypto/external/bsd/netpgp/dist/src/libmj/libmj.3: revision 1.9
crypto/external/bsd/netpgp/dist/src/lib/libnetpgp.3: revision 1.20
crypto/external/bsd/netpgp/dist/src/lib/libnetpgp.3: revision 1.21
crypto/external/bsd/netpgp/dist/src/lib/libnetpgp.3: revision 1.22
crypto/external/bsd/netpgp/dist/src/netpgpverify/netpgpverify.1: revision 1.12
crypto/external/bsd/netpgp/dist/src/lib/libnetpgp.3: revision 1.23
crypto/external/bsd/netpgp/dist/src/netpgpverify/netpgpverify.1: revision 1.13
crypto/external/bsd/netpgp/dist/src/lib/libnetpgp.3: revision 1.19

Some further changes from PR bin/48395.

Drop superfluous zero prefix for single digit number days.
heads up by wiz

Break down explanation of netpgp_init to make it easier to extend.

Document how the userid is obtained.

Remove trailing whitespace.

Add the following functions to the list (TODO - add descriptions)
netpgp_unsetvar
netpgp_list_keys_json
netpgp_match_keys
netpgp_match_keys_json
netpgp_match_pubkeys
netpgp_validate_sigs
netpgp_format_json

Remove netpgp_match_list_keys() as function does not exist

Add missing output file to netpgp_verify_file() argument list

Sprinkle const to arguments

(martin)