ClangCodeModel: Fix clangd highlighting of string literals

... passed to macros defined in a different file.
This amends e77e57420a. Contrary to our expectation, it is possible that
AST nodes that are marked as belonging (only) to a header file can
contain child nodes that belong to the main file.

Fixes: QTCREATORBUG-26553
Change-Id: I4d1d877d8e1e2dcf7d81b63aa98e1149b5514e3f
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/clangcodemodel/clangdclient.cpp

@@ -3640,12 +3640,11 @@ void ExtraHighlightingResultsCollector::visitNode(const AstNode &node)
     if (m_future.isCanceled())
         return;
     switch (node.fileStatus(m_filePath)) {
-    case AstNode::FileStatus::Foreign:
-        return;
     case AstNode::FileStatus::Ours:
     case AstNode::FileStatus::Unknown:
         collectFromNode(node);
         [[fallthrough]];
+    case AstNode::FileStatus::Foreign:
     case ClangCodeModel::Internal::AstNode::FileStatus::Mixed: {
         const auto children = node.children();
         if (!children)