Fix libxml2 2.12.x build issues.
https://github.com/php/php-src/commit/8a95e616b91ac0eeedba90a61e36e652919763f2
https://github.com/php/php-src/commit/0a39890c967aa57225bb6bdf4821aff7a3a3c082
--- a/ext/dom/document.c
+++ b/ext/dom/document.c
@@ -23,6 +23,7 @@
 #if defined(HAVE_LIBXML) && defined(HAVE_DOM)
 #include "php_dom.h"
 #include <libxml/SAX.h>
+#include <libxml/xmlsave.h>
 #ifdef LIBXML_SCHEMAS_ENABLED
 #include <libxml/relaxng.h>
 #include <libxml/xmlschemas.h>
--- a/ext/libxml/libxml.c	2023-08-03 12:13:08.000000000 -0500
+++ b/ext/libxml/libxml.c	2024-05-17 08:58:49.000000000 -0500
@@ -481,7 +481,11 @@
 	xmlResetError((xmlErrorPtr) ptr);
 }
 
-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;
@@ -732,7 +736,11 @@
 	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);
 
@@ -1035,11 +1043,9 @@
 /* {{{ Retrieve last error from libxml */
 PHP_FUNCTION(libxml_get_last_error)
 {
-	xmlErrorPtr error;
-
 	ZEND_PARSE_PARAMETERS_NONE();
 
-	error = xmlGetLastError();
+	const xmlError *error = xmlGetLastError();
 
 	if (error) {
 		object_init_ex(return_value, libxmlerror_class_entry);
--- a/ext/libxml/php_libxml.h
+++ b/ext/libxml/php_libxml.h
@@ -35,6 +35,7 @@ extern zend_module_entry libxml_module_entry;
 
 #include "zend_smart_str.h"
 #include <libxml/tree.h>
+#include <libxml/parser.h>
 
 #define LIBXML_SAVE_NOEMPTYTAG 1<<2