re PR target/53256 ([avr] Attribute 'interrupt' shall override attribute 'signal')

re PR target/53256 ([avr] Attribute 'interrupt' shall override attribute 'signal')

	PR target/53256
	* config/avr/elf.h (ASM_DECLARE_FUNCTION_NAME): Remove.
	* config/avr/avr-protos.h (avr_asm_declare_function_name): Remove.
	* config/avr/avr.h (struct machine_function): Add attributes_checked_p.
	* config/avr/avr.c (avr_asm_declare_function_name): Remove.
	(expand_prologue): Move initialization of cfun->machine->is_naked,
	is_interrupt, is_signal, is_OS_task, is_OS_main from here to...
	(avr_set_current_function): ...this new static function.
	(TARGET_SET_CURRENT_FUNCTION): New define.
	(avr_function_ok_for_sibcall): Use cfun->machine->is_* instead of
	checking attributes of current_function_decl.
	(avr_regs_to_save): Ditto.
	(signal_function_p): Rename to avr_signal_function_p.
	(interrupt_function_p): Rename to avr_interrupt_function_p.
	* doc/extend.texi (Function Attributes): Better explanation of
	'interrupt' and 'signal' for AVR. Move 'ifunc' down to establish
	alphabetical order.

From-SVN: r187342