/:
* configure.ac: Call AC_DISABLE_OPTION_CHECKING.
(baseargs): Add --disable-option-checking.
* configure: Regenerate.
config/:
* override.m4 (AC_DISABLE_OPTION_CHECKING): Define to be
empty if not defined, to avoid error with 2.59.
(_AC_LANG_IO_PROGRAM): When the Autoconf version is exactly
2.64, avoid per-language instances to drop fopen from test
program.
