* LitTable.java (emit): If a cycle is seen, look for an "init"
	method before checked for a "set" method.  The former is more
	appropriate for immutable-after-initialization methods.

	* PairWithPosition.java (init): New method.
	(readExternal): Use new init method.

	* module3.scm (all-zeros): Add test for Savannah bug #43233
	"Dumping circular literals".
	* obj-test.scm: Test all-zeros.