Always good to return values.
 [jmk] --rw-rw-r-- M 960117 glenda sys 679 Dec  8 09:33 sys/src/ape/lib/ap/stdio/setvbuf.c
	/n/sourcesdump/2005/1208/plan9/sys/src/ape/lib/ap/stdio/setvbuf.c:34,39 - 
	/n/sourcesdump/2005/1209/plan9/sys/src/ape/lib/ap/stdio/setvbuf.c:34,39
	  }
	  int _IO_setvbuf(FILE *f){
	  	if(f==stderr || (f==stdout && isatty(1)))
	- 		setvbuf(f, (char *)0, _IOLBF, BUFSIZ);
	- 	else setvbuf(f, (char *)0, _IOFBF, BUFSIZ);
	+ 		return setvbuf(f, (char *)0, _IOLBF, BUFSIZ);
	+ 	return setvbuf(f, (char *)0, _IOFBF, BUFSIZ);
	  }