include/starpu_util.h: invert the if statement

include/starpu_util.h

@@ -46,7 +46,7 @@ extern "C"
 
 #define STARPU_ABORT()		abort()
 
-#if defined(STARPU_HAVE_WINDOWS)
+#if !defined(STARPU_HAVE_WINDOWS)
 #  define STARPU_CHECK_RETURN_VALUE(err, message) {if (err < 0) { \
 			char xmessage[256]; strerror_r(-err, xmessage, 256); \
 			fprintf(stderr, "StarPU function <%s> returned unexpected value: <%d:%s>\n", message, err, xmessage); \