Another small fix to implementation of -fdump-ada-spec

Another small fix to implementation of -fdump-ada-spec

This avoids generating invalid Ada code for function with a multidimensional
array parameter and also cleans things up left and right.

gcc/c-family/
	* c-ada-spec.cc (check_type_name_conflict): Add guard.
	(is_char_array): Simplify.
	(dump_ada_array_type): Use strip_array_types.
	(dump_ada_node) <POINTER_TYPE>: Deal with anonymous array types.
	(dump_nested_type): Use strip_array_types.