Allow uses of interface types to verify.  This is not really
	type-safe, but it matches what Sun does, and is OK as long as
	there are appropriate run-time checks.
	* verify.c (merge_types):  If merging two interface types,
	just set the result to java.lang.Object.
	* expr.c (pop_type):  Any interface is matches by java.lang.Object.

From-SVN: r23657