sort of new branch: next

[Jim Meyering]

I've pushed a few changes to a new "next" branch.
I expect to rebase it against master.

  $ g shortlog HEAD ^master
        build: use dist-xz, not dist-lzma
        cleanup/modernize: don't test HAVE_MBRTOWC; now gnulib provides it
        portability: accommodate gnulib's getaddrinfo change
        maint: move coreutils-specific syntax check rules into cfg.mk
        maint: tighten m4 AC_ quoting check
        maint: use more sc_-prefixed names
        maint: factor out common code; prohibit use of HAVE_MBRTOWC
        bootstrap: don't use cmp's -s option when reading from a pipe

The first (dist-xz) will probably wait until the first beta release
of xz (aka next-gen lzma).

The rest should migrate to "master" pretty quickly.

Feedback welcome.