cd9660: Apply the file and directory mode masks bits to all 12 access bits

[jhb]

Summary

This permits the mask bits to control the upper 3 bits used for setuid,
setgid, and sticky permissions. While here, clarify the manpage language
as non-Rockridge volumes with extended attributes can also supply users
and groups along with permissions.

[olce]

Thanks, and also for amending the doc with more technical details.

[sjg]

sbin/mount_cd9660/mount_cd9660.8

91

644 is read and write for owner - no execute

[jhb]

sbin/mount_cd9660/mount_cd9660.8

91

sigh, my bad.

[jhb]

sbin/mount_cd9660/mount_cd9660.8

100

This should also be 555

[jhb]

Correct some permissions constants

[olce]

Sigh, had missed that too. Thanks.

[jhb]

@stevek does this version work ok for you?