bug#9872: hello project web page includes libc and autotools manuals?

Mike, I'm not entirely sure what you meant by your other questions, but
the answer to:

    were other projects also routing via those links ?

is no. The .symlinks within gnu.org/s/libtool/manual were/are
essentially only used by libtool's manuals, within
gnu.org/s/automake/manual only by automake's manuals, etc.

Well, I guess I'm not sure what happened when a cross-referenced manual
referred to yet another external manual, but that's not a case I was
ever worried about (or saw reported).

The basic problem was that a cross-manual link would end up with a url
like "libtool within automake"
 gnu.org/s/automake/manual/libtool/somenode.html.
Hence the .symlinks entry, to make that resolve.

But I'm confused now, because looking at even the earliest automake
manual, https://www.gnu.org/software/automake/manual/1.0/automake.html
the xref to the autoconf manual in the introduction has the good url:
https://www.gnu.org/software/autoconf/manual/autoconf.html#Top

instead of something like the bad ("autoconf within automake") url:
https://www.gnu.org/software/automake/manual/autoconf/autoconf.html#Top

that I would have expected, and surely what was generated with
automake-1.0 or other early-ish releases.

Maybe someone regenerated all the automake manuals at some point.
I don't know, but I have no other explanation.

Best,
Karl