Legacy needs xmlSAX2StartElement() and xmlSAX2EndElement().

Fix compilation with minimum and legacy.
diff --git a/SAX2.c b/SAX2.c
index 33d167e..ec105b6 100644
--- a/SAX2.c
+++ b/SAX2.c
@@ -1078,7 +1078,7 @@
     }
 }
 
-#if defined(LIBXML_SAX1_ENABLED) || defined(LIBXML_HTML_ENABLED) || defined(LIBXML_WRITER_ENABLED) || defined(LIBXML_DOCB_ENABLED)
+#if defined(LIBXML_SAX1_ENABLED) || defined(LIBXML_HTML_ENABLED) || defined(LIBXML_WRITER_ENABLED) || defined(LIBXML_DOCB_ENABLED) || defined(LIBXML_LEGACY_ENABLED)
 /**
  * xmlSAX2AttributeInternal:
  * @ctx: the user data (XML parser context)
@@ -1822,7 +1822,7 @@
 #endif
     nodePop(ctxt);
 }
-#endif /* LIBXML_SAX1_ENABLED || LIBXML_HTML_ENABLE */
+#endif /* LIBXML_SAX1_ENABLED || LIBXML_HTML_ENABLED || LIBXML_LEGACY_ENABLED */
 
 /*
  * xmlSAX2TextNode: