squashfs-tools: Allow setting selinux xattrs through file_context

Add a context-file flag that allows passing an selinux security context
file to set security.selinux xattrs rather than reading xattrs from
filesystem's source directory.

Change-Id: Icad4d38a736137d85835a0eab9650c0c99908721
Signed-off-by: Mohamad Ayyash <mkayyash@google.com>
5 files changed