* gdbarch.sh (value_from_register): New gdbarch function.

	* gdbarch.sh (value_from_register): New gdbarch function.
	* gdbarch.c, gdbarch.h: Regenerate.
	* findvar.c (default_value_from_register): New function.
	(value_from_register): Use gdbarch_value_from_register.
	* value.h (default_value_from_register): Declare.
	* spu-tdep.c (spu_convert_register_p, spu_register_to_value,
	spu_value_to_register): Remove.
	(spu_value_from_register): New function.
	(spu_gdbarch_init): Do not call set_gdbarch_convert_register_p,
	set_gdbarch_register_to_value, set_gdbarch_value_to_register.
	Call set_gdbarch_value_from_register.
	* s390-tdep.c (s390_convert_register_p, s390_register_to_value,
	s390_value_to_register): Remove.
	(s390_value_from_register): New function.
	(s390_gdbarch_init): Do not call set_gdbarch_convert_register_p,
	set_gdbarch_register_to_value, set_gdbarch_value_to_register.
	Call set_gdbarch_value_from_register.