[libcxx] [test] In atomics.types.generic/address.pass.cpp, use T(0) for consistency.

[STL_MSFT]

Summary

In atomics.types.generic/address.pass.cpp, use T(0) for consistency.

Fixes MSVC "error C2593: 'operator ==' is ambiguous".

There is almost certainly an MSVC compiler bug involved here (which I haven't reduced yet). However, T(0) was used previously in the test, so using it here increases consistency, in addition to making all compilers happy.

[EricWF]

Never thrilled working around a compiler bug, but this seems harmless enough.

[EricWF]

r273822.

test/std/atomics/atomics.types.generic/address.pass.cpp

do_test()
     assert((obj += std::ptrdiff_t(3)) == T(5*sizeof(X)));
     assert(obj == T(5*sizeof(X)));
     assert((obj -= std::ptrdiff_t(3)) == T(2*sizeof(X)));
     assert(obj == T(2*sizeof(X)));
 
     {
         _ALIGNAS_TYPE(A) char storage[sizeof(A)] = {23};
         A& zero = *new (storage) A();
-        assert(zero == 0);
+        assert(zero == T(0));
         zero.~A();
     }
 }
 
 template <class A, class T>
 void test()
 {
     do_test<A, T>();
     do_test<volatile A, T>();
 }
 
 int main()
 {
     test<std::atomic<int*>, int*>();
 }