Merge pull request #19438 from mhei/22.03-squid-libxml2-backport

[22.03] squid: fix compilation with libxml (fixes #19099)

net/squid/patches/020-libxml-drop-xmlSetFeature.patch

@@ -0,0 +1,10 @@
+--- a/src/esi/Libxml2Parser.cc
++++ b/src/esi/Libxml2Parser.cc
+@@ -91,7 +91,6 @@ ESILibxml2Parser::ESILibxml2Parser(ESIPa
+ 
+     /* TODO: grab the document encoding from the headers */
+     parser = xmlCreatePushParserCtxt(&sax, static_cast<void *>(this), NULL, 0, NULL);
+-    xmlSetFeature(parser, "substitute entities", 0);
+ 
+     if (entity_doc == NULL)
+         entity_doc = htmlNewDoc(NULL, NULL);