Building and installing _only_ architecture-specific man pages raises a number
- The https://www.freebsd.org/cgi/man.cgi is incomplete. As an example, it does not show results for pae(4). The reason for this is that the cgi interface runs on FreeBSD amd64.
- In FreeBSD amd64 some manual pages have broken X-refs. See hptrr(4) for an example.
- Also, we have broken links in our Release Notes. This is a consequence of the first point. See https://www.freebsd.org/releases/13.0R/hardware/#proc-i386.
Make MAN_ARCH default to 'all' so we build all the man pages for all the
architectures. The difference in disk space is negligible. Also link
architecture-specific man pages to their own section while keeping their own
namespace (suggested by ceri@).
Some discussion took place here