statfs.2: Update MAGIC constants

Most of the updates are taken from /usr/include/linux/magic.h,
some were found by grepping the Linux source code.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
statfs.2: fstatfs(2) was broken on file descriptors from pipe(2)

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
statfs.2: Minor tweaks to Cyril Hrubis's "statfs() broken for pipe FDs" patch

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
statfs.2: Move Cyril Hrubis's "statfs() broken for pipe FDs" patch to BUGS

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
statfs.2: Correct kernel version for "statfs() broken for pipe FDs" bug

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>