set the default file size to the largest vlong.
`& ~iosize' in the old code just looks like a bug.

Reference: /n/sources/patch/applied/scuzz-file-size-vlong
Date: Tue Dec  6 10:02:22 CET 2005

--- /sys/src/cmd/scuzz/scuzz.c	Tue Dec  6 10:00:49 2005
+++ /sys/src/cmd/scuzz/scuzz.c	Tue Dec  6 10:00:44 2005
@@ -134,7 +134,7 @@
 	char *p;
 
 	iosize = maxiosize;
-	nbytes = 0x7FFFFFFFFFFFULL & ~iosize;
+	nbytes = ~0ULL >> 1;
 	switch(argc){
 
 	default:
@@ -193,7 +193,7 @@
 	int fd, pid;
 	char *p;
 
-	nbytes = 0x7FFFFFFF & ~maxiosize;
+	nbytes = ~0ULL >> 1;
 	switch(argc){
 
 	default: