workaround for ${1+"$@"}.
* doc/autoconf.texi (Shell Substitutions): Explain it.
From Oliver Kiddle and Peter Stephenson.
Have M4sh perform minimal shell sanitizing.
* lib/m4sugar/m4sh.at (AS_SHELL_SANITIZE): Split the `_AS_PREPARE_*'
part into...
(_AS_PREPARE): this new macro.
(AS_PREPARE): New.
(AS_INIT): Invoke AS_SHELL_SANITIZE.
* tests/m4sh.at (AT_DATA_LINENO): Use _AS_PREPARE.
Adjust Autoconf and Autotest.
* lib/autoconf/general.m4 (_AC_INIT_DEFAULTS): Don't invoke
AS_SHELL_SANITIZE, AS_INIT did it, but invoke AS_PREPARE.
* lib/autotest/general.m4 (AT_INIT): Likewise.
* lib/autoconf/status.m4 (_AC_OUTPUT_CONFIG_STATUS):
Invoke _AS_PREPARE (not AS_PREPARE) in addition to
AS_SHELL_SANITIZE.
Use this M4sh to generate Autoconf's shell scripts.
* tests/wrapsh.as: New, precursor of wrapsh.in.
* tests/Makefile.am: Include lib/freeze.mk to get the dependencies
on Autotest and M4sh.
($(TESTSUITE)): Use $(autotest_m4f_dependencies).
(wrapsh.in): New target.
* bin/autoconf.as: New, precursor of autoconf.in.
(autoconf.in): New target.
(AC_PROG_CXXCPP, AC_PROG_CPP): Set the current language instead of
just asserting it, since these macros can be called directly.
Reported by Raja R. Harinath.
