[rand.dist.samp.pconst] plus some bug fixes in the tests of the other distributions

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@104224 91177308-0d34-0410-b5e6-96231b3b80d8

test/numerics/rand/rand.dis/rand.dist.samp/rand.dist.samp.pconst/set_param.pass.cpp

@@ -0,0 +1,32 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <random>
+
+// template<class RealType = double>
+// class piecewise_constant_distribution
+
+// void param(const param_type& parm);
+
+#include <random>
+#include <cassert>
+
+int main()
+{
+    {
+        typedef std::piecewise_constant_distribution<> D;
+        typedef D::param_type P;
+        double b[] = {10, 14, 16, 17};
+        double p[] = {25, 62.5, 12.5};
+        P pa(b, b+4, p);
+        D d;
+        d.param(pa);
+        assert(d.param() == pa);
+    }
+}