Port from qAsConst() to std::as_const()

We've been requiring C++17 since Qt 6.0, and our qAsConst use finally
starts to bother us (QTBUG-99313), so time to port away from it
now.

Since qAsConst has exactly the same semantics as std::as_const (down
to rvalue treatment, constexpr'ness and noexcept'ness), there's really
nothing more to it than a global search-and-replace.

Task-number: QTBUG-99313
Change-Id: I88edd91395849574436299b8badda21bb93bea39
Reviewed-by: hjk <hjk@qt.io>

src/plugins/clangcodemodel/clangdsemantichighlighting.cpp

@@ -102,7 +102,7 @@ static QList<BlockRange> cleanupDisabledCode(HighlightingResults &results, const
 
     qCDebug(clangdLogHighlight) << "found" << ifdefedOutRanges.size() << "ifdefed-out ranges";
     if (clangdLogHighlight().isDebugEnabled()) {
-        for (const BlockRange &r : qAsConst(ifdefedOutRanges))
+        for (const BlockRange &r : std::as_const(ifdefedOutRanges))
             qCDebug(clangdLogHighlight) << r.first() << r.last();
     }