* doc/extend.texi (AVR Built-in Functions): Document
	__builtin_avr_nops.
	* config/avr/builtins.def (NOPS): New.
	* config/avr/avr.c (avr_expand_nops): New static function.
	(avr_expand_builtin): Use it to handle AVR_BUILTIN_NOPS.

From-SVN: r238947