* tree.c (substitute_in_expr) <COMPONENT_REF>: Tweak and reformat.
	<tcc_vl_exp>: Call process_call_operands on the new CALL_EXPR.
	Propagate the TREE_READONLY flag without overwriting it.
	(substitute_placeholder_in_expr) <tcc_vl_exp>: Likewise.
	Propagate the TREE_READONLY flag onto the result.
	(process_call_operands): Move around.  Use correct constant value.

From-SVN: r148729