re PR c++/49855 (internal compiler error: in fold_convert_const_int_from_real)

	PR c++/49855
	PR c++/49896
	* cp-tree.def (IMPLICIT_CONV_EXPR): New.
	* call.c (perform_implicit_conversion_flags): Build it
	instead of NOP_EXPR.
	* cp-objcp-common.c (cp_common_init_ts): It's typed.
	* cxx-pretty-print.c (pp_cxx_cast_expression): Handle it.
	(pp_cxx_expression): Likewise.
	* error.c (dump_expr): Likewise.
	* semantics.c (potential_constant_expression_1): Likewise.
	* tree.c (cp_tree_equal): Likewise.
	(cp_walk_subtrees): Likewise.
	* pt.c (iterative_hash_template_arg): Likewise.
	(for_each_template_parm_r): Likewise.
	(type_dependent_expression_p): Likewise.
	(tsubst_copy, tsubst_copy_and_build): Handle IMPLICIT_CONV_EXPR
	and CONVERT_EXPR.
	* cp-tree.h (IMPLICIT_CONV_EXPR_DIRECT_INIT): New.

From-SVN: r179813