[libc++] Avoid <memory> include in locale_win32.h

When `_LIBCPP_NO_EXCEPTIONS` is defined, we end up with compile errors
when targeting MSVCRT:

* Code includes `<new>`
* `<new>` includes `<cstdlib>` in order to get `abort`
* `<cstdlib>` includes `<stdlib.h>`, _before_ the `using ::abort`
* `<stdlib.h>` includes `locale_win32.h`
* `locale_win32.h` includes `<memory>`
* `<memory>` includes `<stdexcept>`
* `<stdexcept>` includes `<cstdlib` for `abort`, but that inclusion gets
  (correctly) ignored because of header guards
* `<stdexcept>` references `_VSTD::abort`, which isn't declared

The easiest solution is to make `locale_win32.h` not include `<memory>`,
by removing the use of `unique_ptr` and manually restoring the locale
instead.

Differential Revision: https://reviews.llvm.org/D24374

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@281641 91177308-0d34-0410-b5e6-96231b3b80d8

src/support/win32/locale_win32.cpp

@@ -10,6 +10,11 @@
 
 #include <locale>
 #include <cstdarg> // va_start, va_end
+#include <memory>
+#include <type_traits>
+
+typedef _VSTD::remove_pointer<locale_t>::type __locale_struct;
+typedef _VSTD::unique_ptr<__locale_struct, decltype(&uselocale)> __locale_raii;
 
 // FIXME: base currently unused. Needs manual work to construct the new locale
 locale_t newlocale( int mask, const char * locale, locale_t /*base*/ )