syntax-check: revert most of 962aa91

syntax-check: revert most of 962aa91

The huge hand-rolled 962aa91 introduces regressions on mingw; this
changeset undoes most of it, save 'bootstrap',
'build-aux/extract-trace' (which are maintained outside of libtool
now) and the new syntax-check added to `cfg.mk'.
* build-aux/general.m4sh, build-aux/ltmain.m4sh, configure.ac,
doc/libtool.texi, libtoolize.m4sh, m4/argz.m4, m4/libtool.m4,
m4/ltdl.m4, tests/bindir.at, tests/defs.m4sh, tests/demo-relink.test,
tests/demo/configure.ac, tests/depdemo-relink.test, tests/destdir.at,
tests/duplicate_conv.at, tests/fail.at, tests/help.at,
tests/libtoolize.at, tests/link-2.test, tests/link-order2.at,
tests/lt_dlopenext.at, tests/mdemo/configure.ac,
tests/mdemo2/configure.ac, tests/need_lib_prefix.at, tests/nocase.at,
tests/pdemo/configure.ac, tests/pic_flag.at, tests/search-path.at,
tests/shlibpath.at, tests/static.at, tests/sysroot.at,
tests/tagtrace.test, tests/testsuite.at, tests/with-pic.at: Reverted.

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