[libcxx] [test] Fix MSVC warning C4244 "conversion from 'X' to 'Y', possible loss of data", part 6/7.

test/std/algorithms/alg.modifying.operations/alg.random.shuffle/random_shuffle_rand.pass.cpp
(Affects 64-bit architectures.) Include <cstddef> so we can take/return std::ptrdiff_t
(instead of int) in random_shuffle()'s RNG. (C++14 D.12 [depr.alg.random.shuffle]/2 says that
difference_type is used, and we're shuffling a plain array.)

test/std/algorithms/alg.sorting/alg.sort/sort/sort.pass.cpp
test/std/algorithms/alg.sorting/alg.sort/stable.sort/stable_sort.pass.cpp
(Affects 64-bit architectures.) Include <iterator> because we're already using iterator_traits.
Then, store the result of subtracting two RanIts as difference_type instead of long
(which truncates on LLP64 architectures like MSVC x64).

test/std/containers/sequences/forwardlist/forwardlist.ops/splice_after_flist.pass.cpp
test/std/containers/sequences/forwardlist/forwardlist.ops/splice_after_one.pass.cpp
(Affects 64-bit architectures.) Include <cstddef> so we can store the result of
subtracting two pointers as std::ptrdiff_t (instead of int).

test/std/input.output/iostream.format/input.streams/istream.unformatted/ignore_0xff.pass.cpp
(Affects 32-bit architectures.) Sometimes, size_t is too small. That's the case here,
where tellg() returns pos_type (N4606 27.7.2.3 [istream.unformatted]/39). Implementations can
have 64-bit pos_type (to handle large files) even when they have 32-bit size_t.

Fixes D27543.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@289110 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/algorithms/alg.modifying.operations/alg.random.shuffle/random_shuffle_rand.pass.cpp

@@ -17,12 +17,13 @@
 
 #include <algorithm>
 #include <cassert>
+#include <cstddef>
 
 #include "test_macros.h"
 
 struct gen
 {
-    int operator()(int n)
+    std::ptrdiff_t operator()(std::ptrdiff_t n)
     {
         return n-1;
     }

test/std/algorithms/alg.sorting/alg.sort/sort/sort.pass.cpp

@@ -16,6 +16,7 @@
 //   sort(Iter first, Iter last);
 
 #include <algorithm>
+#include <iterator>
 #include <cassert>
 
 template <class RI>
@@ -23,9 +24,11 @@ void
 test_sort_helper(RI f, RI l)
 {
     typedef typename std::iterator_traits<RI>::value_type value_type;
+    typedef typename std::iterator_traits<RI>::difference_type difference_type;
+
     if (f != l)
     {
-        long len = l - f;
+        difference_type len = l - f;
         value_type* save(new value_type[len]);
         do
         {

test/std/algorithms/alg.sorting/alg.sort/stable.sort/stable_sort.pass.cpp

@@ -16,6 +16,7 @@
 //   stable_sort(Iter first, Iter last);
 
 #include <algorithm>
+#include <iterator>
 #include <cassert>
 
 template <class RI>
@@ -23,9 +24,11 @@ void
 test_sort_helper(RI f, RI l)
 {
     typedef typename std::iterator_traits<RI>::value_type value_type;
+    typedef typename std::iterator_traits<RI>::difference_type difference_type;
+
     if (f != l)
     {
-        long len = l - f;
+        difference_type len = l - f;
         value_type* save(new value_type[len]);
         do
         {