fix an error message (barf -> sysErrorBelch)

rts/win32/OSMem.c

@@ -30,7 +30,8 @@ void setExecutable (void *p, lnat len, rtsBool exec)
 			exec ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE, 
 			&dwOldProtect) == 0)
     {
-	barf("makeExecutable: failed to protect 0x%p; error=%lu; old protection: %lu\n",
-	     p, (unsigned long)GetLastError(), (unsigned long)dwOldProtect);
+	sysErrorBelch("makeExecutable: failed to protect 0x%p; old protection: %lu\n",
+                      p, (unsigned long)dwOldProtect);
+        stg_exit(EXIT_FAILURE);
     }
 }