Issue #7117 (backport py3k float repr) continued:
 - add double endianness detection to configure script
 - add configure-time check to see whether we can use inline
   assembly to get and set x87 control word in configure script
 - add functions to get and set x87 control word in Python/pymath.c
 - add pyport.h logic to determine whether it's safe to use the
   short float repr or not
diff --git a/PC/pyconfig.h b/PC/pyconfig.h
index d4524c8..c9cd2c0 100644
--- a/PC/pyconfig.h
+++ b/PC/pyconfig.h
@@ -749,4 +749,8 @@
    socket handles greater than FD_SETSIZE */
 #define Py_SOCKET_FD_CAN_BE_GE_FD_SETSIZE
 
+/* Define if C doubles are 64-bit IEEE 754 binary format, stored with the
+   least significant byte first */
+#define DOUBLE_IS_LITTLE_ENDIAN_IEEE754 1
+
 #endif /* !Py_CONFIG_H */