Added a define check for __x86_64__.
diff --git a/configure b/configure
index 3570646..28e87f0 100755
--- a/configure
+++ b/configure
@@ -18414,6 +18414,37 @@
LINTFLAGS="$LINTFLAGS -D__i386__"
fi
;;
+ *x86_64*) echo "$as_me:$LINENO: checking whether we need to define __x86_64__" >&5
+echo $ECHO_N "checking whether we need to define __x86_64__... $ECHO_C" >&6
+if test "${ac_cv_cpp_def___x86_64__+set}" = set; then
+ echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+ cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h. */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h. */
+#ifndef __x86_64__
+yes
+#endif
+_ACEOF
+if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
+ $EGREP "yes" >/dev/null 2>&1; then
+ ac_cv_cpp_def___x86_64__=yes
+else
+ ac_cv_cpp_def___x86_64__=no
+fi
+rm -f conftest*
+
+fi
+echo "$as_me:$LINENO: result: $ac_cv_cpp_def___x86_64__" >&5
+echo "${ECHO_T}$ac_cv_cpp_def___x86_64__" >&6
+if test $ac_cv_cpp_def___x86_64__ = yes; then
+ CFLAGS="$CFLAGS -D__x86_64__"
+ LINTFLAGS="$LINTFLAGS -D__x86_64__"
+fi
+ ;;
*alpha*) echo "$as_me:$LINENO: checking whether we need to define __ALPHA__" >&5
echo $ECHO_N "checking whether we need to define __ALPHA__... $ECHO_C" >&6
if test "${ac_cv_cpp_def___ALPHA__+set}" = set; then
