sysctl: don't write '\0' at the end of buffer in a sysctl file

It isn't required. The kernel has a bug in handling auto_msgmni and
if we send extra symbols, a new value isn't applied.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

sysctl.c

@@ -72,7 +72,7 @@ static int sysctl_write_##__type(int fd,				\
 	int i, ret = -1;						\
 	int off = 0;							\
 									\
-	for (i = 0; i < nr && off < sizeof(buf) - 2; i++) {		\
+	for (i = 0; i < nr && off < sizeof(buf) - 1; i++) {		\
 		snprintf(&buf[off], sizeof(buf) - off, __fmt, arg[i]);	\
 		off += strlen(&buf[off]);				\
 	}								\
@@ -87,8 +87,7 @@ static int sysctl_write_##__type(int fd,				\
 	while (off > 0 && isspace(buf[off - 1]))			\
 		off--;							\
 	buf[off + 0] = '\n';						\
-	buf[off + 1] = '\0';						\
-	ret = write(fd, buf, off + 2);					\
+	ret = write(fd, buf, off + 1);					\
 	if (ret < 0) {							\
 		pr_perror("Can't write %s", req->name);			\
 		ret = -1;						\