Fixed math.copysign() on Windows
diff --git a/Modules/mathmodule.c b/Modules/mathmodule.c
index 2c6262d..44a9d93 100644
--- a/Modules/mathmodule.c
+++ b/Modules/mathmodule.c
@@ -133,14 +133,16 @@
       "cos(x)\n\nReturn the cosine of x (measured in radians).")
 FUNC1(cosh, cosh,
       "cosh(x)\n\nReturn the hyperbolic cosine of x.")
-#if defined(MS_WINDOWS) || defined(HAVE_COPYSIGN)
+
 #ifdef MS_WINDOWS
-FUNC2(copysign, _copysign,
-#else
+#  define copysign _copysign
+#  define HAVE_COPYSIGN 1
+#endif
+#ifdef HAVE_COPYSIGN
 FUNC2(copysign, copysign,
+      "copysign(x,y)\n\nReturn x with the sign of y.");
 #endif
-    "copysign(x,y)\n\nReturn x with the sign of y.");
-#endif
+
 FUNC1(exp, exp,
       "exp(x)\n\nReturn e raised to the power of x.")
 FUNC1(fabs, fabs,
@@ -383,7 +385,7 @@
 	{"atan",	math_atan,	METH_O,		math_atan_doc},
 	{"atan2",	math_atan2,	METH_VARARGS,	math_atan2_doc},
 	{"ceil",	math_ceil,	METH_O,		math_ceil_doc},
-#if defined(MS_WINDOWS) || defined(HAVE_COPYSIGN)
+#ifdef HAVE_COPYSIGN
 	{"copysign",	math_copysign,	METH_VARARGS,	math_copysign_doc},
 #endif
 	{"cos",		math_cos,	METH_O,		math_cos_doc},