Add (undocumented) sysr1 builtin, useful during kernel debugging.
 [rsc] --rw-rw-r-- M 28433 glenda sys 20156 Sep 19 06:49 sys/src/cmd/acid/builtin.c
	/n/sourcesdump/2005/0919/plan9/sys/src/cmd/acid/builtin.c:39,44 - 
	/n/sourcesdump/2005/0920/plan9/sys/src/cmd/acid/builtin.c:39,45
	  void	interpret(Node*, Node*);
	  void	include(Node*, Node*);
	  void	regexp(Node*, Node*);
	+ void dosysr1(Node*, Node*);
	  
	  typedef struct Btab Btab;
	  struct Btab
	/n/sourcesdump/2005/0919/plan9/sys/src/cmd/acid/builtin.c:73,78 - 
	/n/sourcesdump/2005/0920/plan9/sys/src/cmd/acid/builtin.c:74,80
	  	"status",	status,
	  	"stop",		stop,
	  	"strace",	strace,
	+ 	"sysr1",	dosysr1,
	  	"waitstop",	waitstop,
	  	"map",		map,
	  	"interpret",	interpret,
	/n/sourcesdump/2005/0919/plan9/sys/src/cmd/acid/builtin.c:109,114 - 
	/n/sourcesdump/2005/0920/plan9/sys/src/cmd/acid/builtin.c:111,127
	  			mkprint(s);
	  		b++;
	  	}
	+ }
	+ 
	+ void
	+ dosysr1(Node *r, Node*)
	+ {
	+ 	extern int sysr1(void);
	+ 	
	+ 	r->op = OCONST;
	+ 	r->type = TINT;
	+ 	r->fmt = 'D';
	+ 	r->ival = sysr1();
	  }
	  
	  void