Nico Rieck: Currently _MSC_VER and _WIN32 are used to guard code which is

MSVC-specific, MSVCRT-specific, or Windows-specific. Because Clang can
also define _MSC_VER, and MSVCRT is not necessarily the only C runtime,
these macros should not be used interchangeably.

This patch divides all Windows-related bits into the aforementioned
categories. Two new macros are introduced:

- _LIBCPP_MSVC: Defined when compiling with MSVC. Detected using
  _MSC_VER, excluding Clang.
- _LIBCPP_MSVCRT: Defined when using the Microsoft CRT. This is the default
   when _WIN32 is defined.

This leaves _WIN32 for code using the Windows API.

This also corrects the spelling of _LIBCP_HAS_IS_BASE_OF to _LIBCPP_HAS_IS_BASE_OF.

Nico, please prepare a patch for CREDITS.TXT, thanks.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@187593 91177308-0d34-0410-b5e6-96231b3b80d8

include/algorithm

@@ -3988,10 +3988,10 @@ sort(__wrap_iter<_Tp*> __first, __wrap_iter<_Tp*> __last, _Compare __comp)
     _VSTD::sort<_Tp*, _Comp_ref>(__first.base(), __last.base(), __comp);
 }
 
-#ifdef _MSC_VER
+#ifdef _LIBCPP_MSVC
 #pragma warning( push )
 #pragma warning( disable: 4231)
-#endif // _MSC_VER
+#endif // _LIBCPP_MSVC
 _LIBCPP_EXTERN_TEMPLATE(void __sort<__less<char>&, char*>(char*, char*, __less<char>&))
 _LIBCPP_EXTERN_TEMPLATE(void __sort<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&))
 _LIBCPP_EXTERN_TEMPLATE(void __sort<__less<signed char>&, signed char*>(signed char*, signed char*, __less<signed char>&))
@@ -4025,9 +4025,9 @@ _LIBCPP_EXTERN_TEMPLATE(bool __insertion_sort_incomplete<__less<double>&, double
 _LIBCPP_EXTERN_TEMPLATE(bool __insertion_sort_incomplete<__less<long double>&, long double*>(long double*, long double*, __less<long double>&))
 
 _LIBCPP_EXTERN_TEMPLATE(unsigned __sort5<__less<long double>&, long double*>(long double*, long double*, long double*, long double*, long double*, __less<long double>&))
-#ifdef _MSC_VER
+#ifdef _LIBCPP_MSVC
 #pragma warning( pop )
-#endif  // _MSC_VER
+#endif  // _LIBCPP_MSVC
 
 // lower_bound