Bump autoconf minimum version to 2.61.
diff --git a/configure.in b/configure.in
index e0e1632..ef9601d 100644
--- a/configure.in
+++ b/configure.in
@@ -4,7 +4,7 @@
 m4_define(PYTHON_VERSION, 2.6)
 
 AC_REVISION($Revision$)
-AC_PREREQ(2.59)
+AC_PREREQ(2.61)
 AC_INIT(python, PYTHON_VERSION, http://www.python.org/python-bugs)
 AC_CONFIG_SRCDIR([Include/object.h])
 AC_CONFIG_HEADER(pyconfig.h)