Store per-element parser state in a struct

Make the parser context's "pushTab" point to an array of structs
instead of void pointers. This avoids casting unrelated types to void
pointers, improving readability and portability, and allows for more
efficient packing. Ultimately, the struct could be extended to include
the contents of "nameTab" and "spaceTab", further simplifying the code.

Historically, "pushTab" was only used by the push parser (hence the
name), so the change to the public headers should be safe.

Also remove an unused parameter from xmlParseEndTag2.

include/libxml/parser.h

@@ -169,6 +169,8 @@ typedef enum {
     XML_PARSE_READER = 5
 } xmlParserMode;
 
+typedef struct _xmlStartTag xmlStartTag;
+
 /**
  * xmlParserCtxt:
  *
@@ -280,7 +282,7 @@ struct _xmlParserCtxt {
     int                nsMax;         /* the size of the arrays */
     const xmlChar *   *nsTab;         /* the array of prefix/namespace name */
     int               *attallocs;     /* which attribute were allocated */
-    void *            *pushTab;       /* array of data for push */
+    xmlStartTag       *pushTab;       /* array of data for push */
     xmlHashTablePtr    attsDefault;   /* defaulted attributes if any */
     xmlHashTablePtr    attsSpecial;   /* non-CDATA attributes if any */
     int                nsWellFormed;  /* is the document XML Namespace okay */