Avoid creating useless local bounds around calls

Avoid creating useless local bounds around calls

This prevents the compiler from creating useless local bounds around calls
that take a parameter of an unconstrained array type when the bounds already
exist somewhere else for the actual parameter.

gcc/ada/
	* gcc-interface/decl.c (gnat_to_gnu_subprog_type): Do not demote a
	const or pure function because of a parameter whose type is pointer
	to function.
	* gcc-interface/trans.c (Call_to_gnu): Do not put back a conversion
	between an actual and a formal that are unconstrained array types.
	(gnat_gimplify_expr) <CALL_EXPR>: New case.
	* gcc-interface/utils2.c (build_binary_op): Do not use |= operator.
	(gnat_stabilize_reference_1): Likewise.
	(gnat_rewrite_reference): Likewise.
	(build_unary_op): Do not clear existing TREE_CONSTANT on the result.
	(gnat_build_constructor): Also accept the address of a constant
	CONSTRUCTOR as constant element.