* NEWS: Warnings are now generated by default for unknown

* NEWS: Warnings are now generated by default for unknown
--enable-* and --with-* options.
* doc/autoconf.texi (Option Checking): Renamed from
(Configure Option Checking).  Tighten up the wording a bit.
(External Software, Package Options): Cross-reference to Option
Checking, and use this to shorten our section.
* lib/autoconf/general.m4 (_AC_INIT_PARSE_ARGS): Prefer test -n
"$x" to test "x$foo" != x.
* lib/autoconf/status.m4 (AC_OUTPUT): Likewise.
Don't warn if $enable_option_checking is "no".
* lib/autoconf/general.m4 (_AC_INIT_PARSE_ARGS): Initialize
ac_unrecognized_opts to the empty string.
Don't echo the unrecognized opts, as this might mishandle
backslashes or leading -.
(AC_PRESERVE_HELP_ORDER): Put the --disable-option-checking
usage next to the other --disable-FEATURE options in the
help string.

2006-12-18  Steven G. Johnson  <stevenj@alum.mit.edu>

* lib/autoconf/general.m4 (_AC_INIT_DEFAULTS, _AC_INIT_PARSE_ARGS):
(_AC_INIT_PARSE_ENABLE2, _AC_INIT_HELP, _AC_ENABLE_IF):
Print warning for unrecognized --with and --enable options
(AC_DISABLE_OPTION_CHECKING): New macro to disable warnings.
* lib/autoconf/status.m4 (AC_CONFIG_SUBDIRS, _AC_OUTPUT_SUBDIRS):
Disable option checking when subdirs are configured.
(AC_OUTPUT): If warnings are enabled, print warning about
unrecognized --with and --enable options at the end of
the configure output (as well as at the beginning).
* doc/autoconf.texi (Option Checking): New node.
Document new option warning functionality.