include/starpu_config.h.in: add macro STARPU_HAVE_STRERROR_R which is needed in public API

include/starpu_config.h.in

@@ -1,7 +1,7 @@
 /* StarPU --- Runtime system for heterogeneous multicore architectures.
  *
  * Copyright (C) 2009-2016  Université de Bordeaux
- * Copyright (C) 2010, 2011, 2012, 2013, 2015, 2016  CNRS
+ * Copyright (C) 2010, 2011, 2012, 2013, 2015, 2016, 2017  CNRS
  * Copyright (C) 2014  INRIA
  *
  * StarPU is free software; you can redistribute it and/or modify
@@ -150,5 +150,6 @@ typedef ssize_t starpu_ssize_t;
 #undef STARPU_HAVE_DARWIN
 
 #undef STARPU_HAVE_CXX11
+#undef STARPU_HAVE_STRERROR_R
 
 #endif