syntax-check: fix violations and implement sc_old_style_quoting.

syntax-check: fix violations and implement sc_old_style_quoting.

Modern GNU ASCII quoting in output and comments is done
'like this'.
* cfg.mk (sc_old_style_quoting): Try to catch most instances
of `old style quoting' so that it is not accidentally re-
introduced to the code.
* HACKING, Makefile.am, NEWS, PORTING, README, TODO, bootstrap,
bootstrap.conf, build-aux/edit-readme-alpha,
build-aux/git-hooks/commit-msg, build-aux/ltmain.in,
doc/libtool.texi, gl/build-aux/bootstrap.in,
gl/build-aux/extract-trace, gl/build-aux/funclib.sh,
gl/build-aux/inline-source, gl/build-aux/options-parser,
libltdl/libltdl/slist.h, libltdl/loaders/loadlibrary.c,
libltdl/ltdl.c, libltdl/slist.c, libtoolize.in, m4/argz.m4,
m4/libtool.m4, m4/ltdl.m4, m4/ltoptions.m4, m4/ltsugar.m4,
tests/cmdline_wrap.at, tests/configure-iface.at, tests/demo.at,
tests/depdemo.at, tests/deplib-in-subdir.at,
tests/deplibs-mingw.at, tests/destdir.at, tests/execute-mode.at,
tests/f77demo.at, tests/fail.at, tests/inherited_flags.at,
tests/libtool.at, tests/libtoolize.at, tests/lt_dladvise.at,
tests/lt_dlexit.at, tests/mdemo.at, tests/need_lib_prefix.at,
tests/old-ltdl-iface.at, tests/old-m4-iface.at, tests/static.at,
tests/stresstest.at, tests/testsuite.at, tests/versioning.at:
Convert to upright quotes.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>