[libcxx] [test] Fix shadow warnings.

[STL_MSFT]

Summary

Fix MSVC shadow warnings in a newly added test, by renaming local variables.

[mclow.lists]

LGTM

[STL_MSFT]

Thanks Marshall. Can either you or Eric commit this?

[EricWF]

r283618.

test/std/utilities/utility/forward/move.pass.cpp

struct A {
     A() {}
     A(const A&) {++copy_ctor;}
     A(A&&) {++move_ctor;}
     A& operator=(const A&) = delete;
 };
 
 constexpr bool test_constexpr_move() {
 #if TEST_STD_VER > 11
-    int x = 42;
-    const int cx = x;
-    return std::move(x) == 42
-        && std::move(cx) == 42
-        && std::move(static_cast<int&&>(x)) == 42
-        && std::move(static_cast<int const&&>(x)) == 42;
+    int y = 42;
+    const int cy = y;
+    return std::move(y) == 42
+        && std::move(cy) == 42
+        && std::move(static_cast<int&&>(y)) == 42
+        && std::move(static_cast<int const&&>(y)) == 42;
 #else
     return true;
 #endif
 }
 
 int main()
 {
     { // Test return type and noexcept.
int main()
     }
     { // test on a move only type
         move_only mo;
         test(std::move(mo));
         test(source());
     }
 #if TEST_STD_VER > 11
     {
-        constexpr int x = 42;
-        static_assert(std::move(x) == 42, "");
+        constexpr int y = 42;
+        static_assert(std::move(y) == 42, "");
         static_assert(test_constexpr_move(), "");
     }
 #endif
 #if TEST_STD_VER == 11 && defined(_LIBCPP_VERSION)
     // Test that std::forward is constexpr in C++11. This is an extension
     // provided by both libc++ and libstdc++.
     {
-        constexpr int x = 42;
-        static_assert(std::move(x) == 42, "");
+        constexpr int y = 42;
+        static_assert(std::move(y) == 42, "");
     }
 #endif
 }