configure: Define _WIN64 when building on a 64-bit platform.
diff --git a/configure b/configure
index ece71b4..6c25767 100755
--- a/configure
+++ b/configure
@@ -24167,6 +24167,37 @@
CFLAGS="$CFLAGS -D__x86_64__"
LINTFLAGS="$LINTFLAGS -D__x86_64__"
fi
+
+ { echo "$as_me:$LINENO: checking whether we need to define _WIN64" >&5
+echo $ECHO_N "checking whether we need to define _WIN64... $ECHO_C" >&6; }
+if test "${ac_cv_cpp_def__WIN64+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 _WIN64
+yes
+#endif
+_ACEOF
+if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
+ $EGREP "yes" >/dev/null 2>&1; then
+ ac_cv_cpp_def__WIN64=yes
+else
+ ac_cv_cpp_def__WIN64=no
+fi
+rm -f conftest*
+
+fi
+{ echo "$as_me:$LINENO: result: $ac_cv_cpp_def__WIN64" >&5
+echo "${ECHO_T}$ac_cv_cpp_def__WIN64" >&6; }
+if test $ac_cv_cpp_def__WIN64 = yes; then
+ CFLAGS="$CFLAGS -D_WIN64"
+ LINTFLAGS="$LINTFLAGS -D_WIN64"
+fi
;;
*alpha*) { echo "$as_me:$LINENO: checking whether we need to define __ALPHA__" >&5
echo $ECHO_N "checking whether we need to define __ALPHA__... $ECHO_C" >&6; }
