Fix GH-14563: Build failure with libxml2 v2.13.0

Remove xmlErrMemory from the export section for Windows, this fixes the
build. Even though the original function was renamed [1] it is hidden,
so removing this should be sufficient and not be a BC break.

[1] GNOME/libxml2@1304369

Closes GH-14719.

Author: ndossche

NEWS

@@ -12,6 +12,9 @@ PHP                                                                        NEWS
 - Dom:
   . Fixed bug GH-14702 (DOMDocument::xinclude() crash). (nielsdos)
 
+- LibXML:
+  . Fixed bug GH-14563 (Build failure with libxml2 v2.13.0). (nielsdos)
+
 - Phar:
   . Fixed bug GH-14603 (null string from zip entry).
     (David Carlier)

ext/libxml/php_libxml2.def

@@ -345,7 +345,6 @@ xmlElemDump
 xmlEncodeEntities
 xmlEncodeEntitiesReentrant
 xmlEncodeSpecialChars
-xmlErrMemory
 xmlFileClose
 xmlFileMatch
 xmlFileOpen