GMP version 5.1.0 (and, presumably, later versions) defines std::numeric_limits.

commit 9f843aecc23981aec6ed1eaa8be06e6786a47f0d
Author: Roberto Bagnara <bagnara@cs.unipr.it>
Date:   Wed Dec 19 08:42:19 2012 +0100

    GMP version 5.1.0 (and, presumably, later versions) defines std::numeric_limits.