QSmallByteArray: add missing Windows min/max macro protection

This is in preparation of moving the type into its own header file.

Amends 29050fa65b7c755ec3238ff0cc238c626832bc8c.

Task-number: QTCREATORBUG-28838
Pick-to: 6.5
Change-Id: I9dd35c1adc9b1ea32d8616ace89975c07a380ae4
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
(cherry picked from commit 4a1e0ddeae566ab730c1505bb654471509ba0cfa)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/corelib/tools/qcryptographichash.cpp

@@ -128,7 +128,7 @@ template <size_t N>
 class QSmallByteArray
 {
     std::array<quint8, N> m_data;
-    static_assert(N <= std::numeric_limits<std::uint8_t>::max());
+    static_assert(N <= (std::numeric_limits<std::uint8_t>::max)());
     quint8 m_size = 0;
 public:
     QSmallByteArray() = default;