Fix MSVC 2017 build error

Author: hirohira9119

include/fmt/base.h

@@ -326,8 +326,8 @@ using underlying_t = typename std::underlying_type<T>::type;
 template <typename T> using decay_t = typename std::decay<T>::type;
 using nullptr_t = decltype(nullptr);
 
-#if FMT_GCC_VERSION && FMT_GCC_VERSION < 500
-// A workaround for gcc 4.9 to make void_t work in a SFINAE context.
+#if (FMT_GCC_VERSION && FMT_GCC_VERSION < 500) || FMT_MSC_VERSION
+// A workaround for gcc 4.9 and MSVC 2017 to make void_t work in a SFINAE context.
 template <typename...> struct void_t_impl {
   using type = void;
 };