blkid: remove unnecessary header and comment

blkid: remove unnecessary header and comment

The LIST_HEAD macro is not directly used in getsize.c, so
<sys/queue.h> is not needed at all, and could cause confusion at
some later point if the Linux-style list macros are ever used.

Build was verified on MacOS which defined HAVE_SYS_DISK_H true.
I manually inspected the sources for recent *BSD headers to check
if this was needed there or not.  MacOS and FreeBSD <sys/disk.h>
do not use lists at all.  NetBSD and OpenBSD <sys/disk.h> and all
of the <sys/mount.h> headers include <sys/queue.h> internally.

I used http://fxr.watson.org/fxr/source/sys/mount.h?v={OSTYPE}
as a reference, checking both old and new *BSD versions.

Signed-off-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>