Disable option checking in the toplevel, avoid 2.64 fopen glitch.

/:
	* 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.

configure

@@ -1509,6 +1509,7 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 
 
+
 
 
 progname=$0
@@ -6546,6 +6547,7 @@ baseargs="$baseargs --program-transform-name='${gcc_transform_name}'"
 if test "$silent" = yes; then
   baseargs="$baseargs --silent"
 fi
+baseargs="$baseargs --disable-option-checking"
 
 # For the build-side libraries, we just need to pretend we're native,
 # and not use the same cache file.  Multilibs are neither needed nor