set_lsb_release.sh: tell getfattr to use absolute names

Adding --absolute-names to getfattr to let getfattr not to remove
the leading slash, and not to print the warning to stderr.

BUG=chromium:954670
TEST=set_lsb_release.sh xx.bin a b
TEST=`getfattr: Removing leading '/' from absolute path names` not printed
BRANCH=none

Change-Id: I6273151713612746443d5d68a8df530f1146a4a2
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/1712890
Tested-by: Qijiang Fan <fqj@google.com>
Reviewed-by: LaMont Jones <lamontjones@chromium.org>
Commit-Queue: Qijiang Fan <fqj@google.com>
diff --git a/scripts/image_signing/set_lsb_release.sh b/scripts/image_signing/set_lsb_release.sh
index f971b7b..e847abb 100755
--- a/scripts/image_signing/set_lsb_release.sh
+++ b/scripts/image_signing/set_lsb_release.sh
@@ -70,7 +70,7 @@
   cat "${rootfs}/etc/lsb-release"
 
   # Dump security context for lsb-release file
-  getfattr -n security.selinux "${rootfs}/etc/lsb-release"
+  getfattr --absolute-names -n security.selinux "${rootfs}/etc/lsb-release"
 }
 
 main "$@"