PR c++/85462
	* cp-tree.h (tinst_level): Remove in_system_header_p member,
	change refcount member from unsigned char to unsigned short,
	add refcount_infinity static data member, adjust comments.
	* pt.c (tinst_level::refcount_infinity): Define.
	(inc_refcount_use): Remove assert, don't increment if refcount
	is already refcount_infinity, adjust comment.
	(dec_refcount_use): Remove assert, don't decrement if refcount
	is refcount_infinity, adjust comment.
	(push_tinst_level_loc): Formatting fix.

	* g++.dg/cpp0x/pr85462.C: New test.

From-SVN: r259516