[libcxx] [test] Fix mismatches between _aligned_malloc and free() on …

…Windows

This allows getting rid of one case of LIBCXX-WINDOWS-FIXME. The fixme
comment was inaccurate; aligned allocation functions are provided these
days, but the test kept failing as it was using mismatched allocation
and free functions.

A similar issue was fixed earlier, in
6596778. That test was fixed by
overriding the aligned `operator new` too, and returning a dummy fixed
allocation instead. As this test is libcxx specific, it can use the
internal `std::__libcpp_aligned_free()` instead, to match libcxx's
internal aligned `operator new`.

Differential Revision: https://reviews.llvm.org/D118190

libcxx/test/libcxx/language.support/support.dynamic/libcpp_deallocate.sh.cpp

@@ -9,10 +9,6 @@
 // test libc++'s implementation of align_val_t, and the relevant new/delete
 // overloads in all dialects when -faligned-allocation is present.
 
-// Libc++ defers to the underlying MSVC library to provide the new/delete
-// definitions, which does not yet provide aligned allocation
-// XFAIL: LIBCXX-WINDOWS-FIXME
-
 // XFAIL: LIBCXX-AIX-FIXME
 
 // The dylibs shipped before macosx10.13 do not contain the aligned allocation
@@ -115,14 +111,14 @@ void operator delete(void* p, size_t n)TEST_NOEXCEPT {
 
 #ifndef NO_ALIGN
 void operator delete(void* p, std::align_val_t a)TEST_NOEXCEPT {
-  ::free(p);
+  std::__libcpp_aligned_free(p);
   stats.aligned_called++;
   stats.last_align = static_cast<int>(a);
   stats.last_size = -1;
 }
 
 void operator delete(void* p, size_t n, std::align_val_t a)TEST_NOEXCEPT {
-  ::free(p);
+  std::__libcpp_aligned_free(p);
   stats.aligned_sized_called++;
   stats.last_align = static_cast<int>(a);
   stats.last_size = n;