pattern: Fix compilation of explicit child axis

The child axis is the default axis and should generate XML_OP_ELEM like
the case without an axis.

pattern.c

diff --git a/pattern.c b/pattern.c
index 0877fc1..6fa88f7 100644
--- a/pattern.c
+++ b/pattern.c
@@ -1035,10 +1035,10 @@
 			    goto error;
 			}
 		    } else {
-			PUSH(XML_OP_CHILD, token, URL);
+			PUSH(XML_OP_ELEM, token, URL);
 		    }
 		} else
-		    PUSH(XML_OP_CHILD, name, NULL);
+		    PUSH(XML_OP_ELEM, name, NULL);
 		return;
 	    } else if (xmlStrEqual(name, (const xmlChar *) "attribute")) {
 		XML_PAT_FREE_STRING(ctxt, name)