re PR libstdc++/51795 (linear_congruential_engine doesn't work correctly)

re PR libstdc++/51795 (linear_congruential_engine doesn't work correctly)

2012-04-29  Marc Glisse  <marc.glisse@inria.fr>
	    Paolo Carlini  <paolo.carlini@oracle.com>

	PR libstdc++/51795
	* include/bits/stl_algobase.h (__lg<>(_Size)): Remove.
	(__lg(int), __lg(unsigned), __lg(long), __lg(unsigned long),
	__lg(long long), __lg(unsigned long long)): Define constexpr.
	* include/bits/random.h (_Mod<>): Overcome Schrage's algorithm
	limitations.
	(__mod): Adjust.
	(linear_congruential): Remove FIXME static_assert.
	* include/bits/random.tcc (_Mod<>): Adjust.
	* testsuite/26_numerics/random/linear_congruential_engine/operators/
	51795.cc: New.

Co-Authored-By: Paolo Carlini <paolo.carlini@oracle.com>
From-SVN: r186948