AIX's new compiler, xlC5.x, doesn't allow the use of "friend" to declare

a function prototype.  So we have to decare the function and then
declare it a friend.  When Default arguments are used, they need to
be specified in the function prototype and NOT in the friend declaration.
# 43311
r=dbaron@fas.harvard.edu

content/xslt/src/base/txList.h

@@ -33,6 +33,8 @@
 #include "baseutils.h"
 #include "TxObject.h"
 
+class txListIterator;
+
 /**
  * Represents an ordered list of Object pointers. Modeled after a Java 2 List.
 **/