distro-configs files, autogen.sh options, defaults etc

I am once again pretty confused.

From a high-level point of view, what is the intent:

- Should a new, naïve contributor be able to run just ./autogen.sh
without any options and, assuming his platform is a reasonably well
supported one, get a working, perhaps minimal (i.e. quicker/easier to
build) build? (I think YES.)

- Or are you always expected to pass a --with-distro=YourOS switch? (I
think NO.)

- Surely only official TDF builds are supposed to use
--with-vendor=The Document Foundation ? (Sure, we can't *prevent*
random people from passing whatever they want as --with-vendor, but I
mean we don't want random buillds that somebody might give to a few
friends, or offer to a wider public, to claim to be from TDF, right?)
(I think INDEED.)

Currentlly how configure.in and the distro-configs files work is a bit
confusing, and doesn't really give an impression of any clear overall
policy regarding the above points.

If I understand correctly, the distro-configs files should not contain
any such --enable / --disable switches that are *required* for the
build to succeed on the platform in question. Right? So for instance
the --disable-cairo-canvas should not be in LibreOfficeMacOSX.conf and
LibreOfficeWin32.conf, but instead the enable_cairo_canvas should be
hardcoded as "no" always for MacOSX and Windows?

--tml