Use librt for aio_read too

configure.ac

@@ -335,6 +335,7 @@ fi
 AC_CHECK_FUNC([sched_yield], [AC_DEFINE([STARPU_HAVE_SCHED_YIELD], [1], [Define to 1 if the function sched_yield is available.])])
 
 AC_CHECK_HEADERS([aio.h])
+AC_CHECK_LIB([rt], [aio_read])
 
 AC_CHECK_FUNCS([mkostemp])