run syntax-check rules on gnulib's own sources

[Jim Meyering]

Here's a framework by which "make sc_check" will run
maint.mk's syntax-check rules on gnulib's own sources.
The first patch adds the rule and a new file, cfg.mk
which disables all of the currently-failing tests (many!)
The next few patches enable tests one by one, removing
the test name from the skip-list in cfg.mk and addressing
the problem -- either legitimate (by fixing sources and/or maint.mk)
or false positive (by exempting the affected files via the regexp
variables at the end of cfg.mk).

Just poking semi-randomly, by enabling tests and examining
the resulting "make sc_check" failures, I've found a few easy fixes.

If it's easy to change upstream copies of
build-aux/texinfo.tex and doc/Copyright/assign.future.manual,
I'd be happy to do that (let me know how), and then we
won't need to exempt them.
I went ahead and removed the single trailing blank in
doc/gnu-oids.texi on the principle that it won't be updated
frequently, and it might be easy to fix upstream to match.

[1/8] maint: add framework to run syntax-check rules against
[2/8] maint: remove empty lines at EOF, but excluding
[3/8] maint: enable double-word-prohibiting rule
[4/8] maint: enable sc_prohibit_hash_pjw_without_use
[5/8] maint: enable sc_prohibit_intprops_without_use
[6/8] maint: enable sc_prohibit_cloexec_without_use
[7/8] maint: enable sc_prohibit_openat_without_use
[8/8] maint: enable sc_trailing_blank

Here are the ChangeLog entries:

2012-01-17  Jim Meyering  <address@hidden>

        maint: enable sc_trailing_blank
        * build-aux/pmccabe.css: Remove trailing blanks.
        * doc/acl-cygwin.txt: Likewise.
        * doc/gnu-oids.texi: Likewise
        * cfg.mk: Enable sc_trailing_blank.
        Exempt build-aux/texinfo.tex and doc/Copyright/assign.future.manual.

        maint: enable sc_prohibit_openat_without_use
        * cfg.mk: Enable sc_prohibit_openat_without_use.
        Exempt lib/selinux-at.c.

        maint: enable sc_prohibit_cloexec_without_use
        * cfg.mk: Enable sc_prohibit_cloexec_without_use.
        * lib/dup-safer-flag.c: Don't include "cloexec.h".  Not needed.

        maint: enable sc_prohibit_intprops_without_use
        * cfg.mk: Enable sc_prohibit_intprops_without_use
        * tests/test-nanosleep.c: Don't include "intprops.h".  Not needed.

        maint: enable sc_prohibit_hash_pjw_without_use
        * cfg.mk: Enable sc_prohibit_hash_pjw_without_use.
        * top/maint.mk (sc_prohibit_hash_pjw_without_use): Adjust regexp
        to match any use of \<hash_pjw\>, i.e., not necessarily with a
        following " (".

        maint: enable double-word-prohibiting rule
        * cfg.mk (local-checks-to-skip): Enable sc_prohibit_doubled_word.
        Exempt three files.

        maint: remove empty lines at EOF, but excluding modules/*
        Apply syntax rules at home as well as abroad.  Most changes
        were induced by running this:
          make srcdir=. _build-aux=build-aux -f top/maint.mk \
            sc_prohibit_empty_lines_at_EOF | grep -v modules/ \
            | xargs perl -pi -0777 -e 's/\n\n+$/\n/'
        * cfg.mk (local-checks-to-skip): Enable sc_prohibit_empty_lines_at_EOF.
        Exempt modules/* and two binary files.

        * doc/regexprops-generic.texi: *Add* a newline at EOF.  There was none.
        * doc/Copyright/assign.translation.manual: Remove empty lines at EOF.
        * doc/Copyright/request-assign.future: Likewise.
        * doc/Copyright/request-disclaim.changes: Likewise.
        * doc/INSTALL: Likewise.
        * doc/INSTALL.ISO: Likewise.
        * doc/INSTALL.UTF-8: Likewise.
        * doc/acl-cygwin.txt: Likewise.
        * doc/acl-resources.txt: Likewise.
        * doc/fdl-1.2.texi: Likewise.
        * doc/fdl-1.3.texi: Likewise.
        * doc/fdl.texi: Likewise.
        * lib/argp-pin.c: Likewise.
        * lib/round.c: Likewise.
        * lib/unicase/u16-totitle.c: Likewise.
        * lib/unictype/block_test.c: Likewise.
        * lib/uninorm/canonical-decomposition.c: Likewise.
        * m4/README: Likewise.
        * m4/relocatable-lib.m4: Likewise.
        * tests/test-isnand-nolibm.c: Likewise.
        * tests/test-isnand.c: Likewise.
        * tests/uninorm/NormalizationTest.txt: Likewise.

        maint: add framework to run syntax-check rules against gnulib sources
        * cfg.mk: New file, to disable all currently-failing tests.
        We'll enable them one by one, as they are made to pass.
        * Makefile (sc_maint): New rule.