net/samba420: Fix pkg-plist for bundled talloc

Move share/man/man3/samba-talloc.3.gz to
%%MANPAGES%%%%SAMBA4_BUNDLED_TALLOC%% category in pkg-plist.
Building with BUNDLED_TALLOC set and MANPAGES unset currently breaks
at the packaging step with the following:

===>  Building packages for samba420-4.20.7_7
===>   Building samba420-4.20.7_7
pkg-static: Unable to access file /tmp/_ports/usr/ports/net/samba420/work/stage/usr/local/share/man/man3/samba-talloc.3.gz:No such file or directory
*** Error code 1

PR: 288198
Sponsored by: Klara, Inc.