m4: Update cython_python to use newer AX_PYTHON_DEVEL macro
diff --git a/m4/cython_python.m4 b/m4/cython_python.m4
index ba730d5..5b4a041 100644
--- a/m4/cython_python.m4
+++ b/m4/cython_python.m4
@@ -1,6 +1,6 @@
 AC_DEFUN([CYTHON_PYTHON],[
         AC_REQUIRE([AC_PROG_CYTHON])
-        AC_REQUIRE([AC_PYTHON_DEVEL])
+        AC_REQUIRE([AX_PYTHON_DEVEL])
         test "x$1" != "xno" || cython_shadow=" -noproxy"
         AC_SUBST([CYTHON_PYTHON_OPT],[-python$cython_shadow])
         AC_SUBST([CYTHON_PYTHON_CPPFLAGS],[$PYTHON_CPPFLAGS])