Protect pyconfig.h from multiple inclusions.
diff --git a/configure.in b/configure.in
index 79ace17..07f452d 100644
--- a/configure.in
+++ b/configure.in
@@ -11,11 +11,17 @@
 
 # This is for stuff that absolutely must end up in pyconfig.h.
 # Please use pyport.h instead, if possible.
+AH_TOP([
+#ifndef Py_PYCONFIG_H
+#define Py_PYCONFIG_H
+])
 AH_BOTTOM([
 /* Define the macros needed if on a UnixWare 7.x system. */
 #if defined(__USLC__) && defined(__SCO_VERSION__)
 #define STRICT_SYSV_CURSES /* Don't use ncurses extensions */
 #endif
+
+#endif /*Py_PYCONFIG_H*/
 ])
 
 AC_SUBST(VERSION)