Make get_pretty_representation work on method types

Make get_pretty_representation work on method types

Until now, get_pretty_representation() considered method types just as
function types.  This patch makes it know about them specifically.  This
useful for debugging, at least.

	* include/abg-fwd.h (is_method_type): Declare new overloads for
	naked pointers.
	(get_method_type_name): Declare new functions.
	(get_pretty_representation): Declare new overloads for
	method_type.
	* src/abg-ir.cc (get_function_type_name): If the function type is
	a method type, handle it as such.
	(get_method_type_name): Define new functions.
	(get_pretty_representation): If the function type is a method
	type, handle it as such.
	(get_pretty_representation): Define new overloads for method_type
	and pointer/reference to method_type.
	(is_method_type): Add overloads for naked pointers.

Signed-off-by: Dodji Seketeli <dodji@redhat.com>