* gensupport.c (add_define_attr): New static function.
	(is_predicable): Allow multi-alternative lists for the "predicable"
	attribute.
	(modify_attr_enabled_ce, alter_attrs_for_insn): New static functions.
	(process_one_cond_exec): Call alter_attrs_for_insn.
	* doc/md.texi (Defining Attributes): Mention some standard names.
	(Conditional Execution): Update documentation for "predicable".

From-SVN: r175263