Issue #21958: Define HAVE_ROUND when building with VS 2013 and above.

Patch by Zachary Turner.

Misc/NEWS

@@ -180,6 +180,9 @@ Library
 Build
 -----
 
+- Issue #21958: Define HAVE_ROUND when building with Visual Studio 2013 and
+  above.  Patch by Zachary Turner.
+
 - Issue #15759: "make suspicious", "make linkcheck" and "make doctest" in Doc/
   now display special message when and only when there are failures.
 

PC/pyconfig.h

@@ -436,6 +436,11 @@ Py_NO_ENABLE_SHARED to find out.  Also support MS_NO_COREDLL for b/w compat */
 /* Define to 1 if you have the `copysign' function. */
 #define HAVE_COPYSIGN 1
 
+/* Define to 1 if you have the `round' function. */
+#if _MSC_VER >= 1800
+#define HAVE_ROUND 1
+#endif
+
 /* Define to 1 if you have the `isinf' macro. */
 #define HAVE_DECL_ISINF 1