Backport 0a39890c: Fix libxml2 2.12 build due to API breaks

See https://github.com/php/php-src/actions/runs/7062192818/job/19225478601

(cherry picked from commit fa6a0f80f644932506666beb7c85e4041c4a4646)
(cherry picked from commit 6e8e9f5)

Author: nielsdos

ext/libxml/libxml.c

@@ -530,7 +530,11 @@ static int _php_libxml_free_error(xmlErrorPtr error)
 	return 1;
 }
 
-static void _php_list_set_error_structure(xmlErrorPtr error, const char *msg)
+#if LIBXML_VERSION >= 21200
+static void _php_list_set_error_structure(const xmlError *error, const char *msg)
+#else
+static void _php_list_set_error_structure(xmlError *error, const char *msg)
+#endif
 {
 	xmlError error_copy;
 	int ret;
@@ -784,7 +788,11 @@ PHP_LIBXML_API void php_libxml_ctx_warning(void *ctx, const char *msg, ...)
 	va_end(args);
 }
 
+#if LIBXML_VERSION >= 21200
+PHP_LIBXML_API void php_libxml_structured_error_handler(void *userData, const xmlError *error)
+#else
 PHP_LIBXML_API void php_libxml_structured_error_handler(void *userData, xmlErrorPtr error)
+#endif
 {
 	_php_list_set_error_structure(error, NULL);
 
@@ -1063,9 +1071,7 @@ static PHP_FUNCTION(libxml_use_internal_errors)
    Retrieve last error from libxml */
 static PHP_FUNCTION(libxml_get_last_error)
 {
-	xmlErrorPtr error;
-
-	error = xmlGetLastError();
+	const xmlError *error = xmlGetLastError();
 
 	if (error) {
 		object_init_ex(return_value, libxmlerror_class_entry);

ext/soap/php_sdl.c

@@ -333,7 +333,7 @@ static void load_wsdl_ex(zval *this_ptr, char *struri, sdlCtx *ctx, int include)
 	sdl_restore_uri_credentials(ctx);
 
 	if (!wsdl) {
-		xmlErrorPtr xmlErrorPtr = xmlGetLastError();
+		const xmlError *xmlErrorPtr = xmlGetLastError();
 
 		if (xmlErrorPtr) {
 			soap_error2(E_ERROR, "Parsing WSDL: Couldn't load from '%s' : %s", struri, xmlErrorPtr->message);