Avoid complaint about inconsistent hypot() linkage on NT.
diff --git a/Modules/mathmodule.c b/Modules/mathmodule.c
index e69aea9..4ebb26e 100644
--- a/Modules/mathmodule.c
+++ b/Modules/mathmodule.c
@@ -44,7 +44,9 @@
 
 
 #if defined(HAVE_HYPOT)
+#ifndef _MSC_VER
 extern double hypot PROTO((double, double));
+#endif
 #else
 double hypot(x,y)
 	double x;