Cherry-pick 270977@main (1bad176). https://bugs.webkit.org/show_bug.c…

…gi?id=265128

    Build fails with libxml2 version 2.12.0 due to API change
    https://bugs.webkit.org/show_bug.cgi?id=265128

    Reviewed by Philippe Normand.

    Starting with libxml2 2.12.0, the API has changed the const-ness of the
    xmlError pointers, which results in a build error due to a mismatched
    type in the parsing error callback. This papers over the difference by
    using preprocessor conditionals.

    * Source/WebCore/xml/XSLTProcessor.h: Use const when building against
      libxml2 2.12.0 or newer.
    * Source/WebCore/xml/XSLTProcessorLibxslt.cpp:
    (WebCore::XSLTProcessor::parseErrorFunc): Ditto.

    Canonical link: https://commits.webkit.org/270977@main

Source/WebCore/xml/XSLTProcessor.h

@@ -61,7 +61,11 @@ class XSLTProcessor : public RefCounted<XSLTProcessor> {
 
     void reset();
 
+#if LIBXML_VERSION >= 21200
+    static void parseErrorFunc(void* userData, const xmlError*);
+#else
     static void parseErrorFunc(void* userData, xmlError*);
+#endif
     static void genericErrorFunc(void* userData, const char* msg, ...);
 
     // Only for libXSLT callbacks

Source/WebCore/xml/XSLTProcessorLibxslt.cpp

@@ -59,7 +59,11 @@ void XSLTProcessor::genericErrorFunc(void*, const char*, ...)
     // It would be nice to do something with this error message.
 }
 
+#if LIBXML_VERSION >= 21200
+void XSLTProcessor::parseErrorFunc(void* userData, const xmlError* error)
+#else
 void XSLTProcessor::parseErrorFunc(void* userData, xmlError* error)
+#endif
 {
     PageConsoleClient* console = static_cast<PageConsoleClient*>(userData);
     if (!console)