bsdinstall/distfetch: replace libdialog with libbsddialog

[asiciliano]

Summary

Replace LGPL libdialog with permissive libbsddialog.
Moreover diversify the error messages, unfortunately the numbers of errors during the fetching is growing (mainly in VM, example https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=261653), so we can find quickly the exact point of failure.

Test Plan

% cd usr.sbin/bsdinstall/distfetch/
% make
% mkdir download
% env DISTRIBUTIONS="kernel.txz lib32.txz tests.txz" BSDINSTALL_DISTDIR="./download" BSDINSTALL_DISTSITE="https://download.freebsd.org/ftp/snapshots/amd64/14.0-CURRENT/" ./distfetch

                                                             
┌────────┤Fetching Distribution├───────┐                     
│ kernel.txz           [    Done     ] │                     
│ lib32.txz            [    Done     ] │                     
│ tests.txz            [    Done     ] │                     
│                                      │                     
│ Fetching distribution completed      │                     
│                                      │                     
│  ┌─Overall Progress───────────────┐  │                     
│  │              100%              │  │                     
│  └────────────────────────────────┘  │                     
└──────────────────────────────────────┘

% ls download/
kernel.txz lib32.txz tests.txz
% make clean ; make cleandir
% rm -R download/

[emaste]

usr.sbin/bsdinstall/distfetch/Makefile

5–6

This is because we're not (yet/currently) installing bsddialog's headers?

[asiciliano]

usr.sbin/bsdinstall/distfetch/Makefile

5–6

Thank you for the comment,

Probably because the library is private,
I follow @bapt' s template (https://cgit.freebsd.org/src/tree/usr.sbin/tzsetup/Makefile) for Makefiles,
of course I can change if you prefer other solutions.

[emaste]

Probably because the library is private,

Ah right, this is necessary for private libraries.