re PR libstdc++/57920 ([c++11] Linux: std::random_device reads too much from /dev/urandom)

2013-07-22  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/57920
	* src/c++11/random.cc (random_device::_M_getval): If possible, use
	read instead of std::fread.
	* include/std/random: Do not include <cstdio> unnecessarily.

From-SVN: r201133