Fix libxml2 2.12.x build issues.
https://github.com/php/php-src/commit/0a39890c967aa57225bb6bdf4821aff7a3a3c082
--- ext/soap/php_sdl.c.orig	2010-11-08 05:34:32.000000000 -0600
+++ ext/soap/php_sdl.c	2024-05-20 15:50:36.000000000 -0500
@@ -300,7 +300,7 @@
 	sdl_restore_uri_credentials(ctx TSRMLS_CC);
 	
 	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);
 		} else {