Fix ls_tests:o_flag with ZFS TMPDIR

Unlike UFS or TMPFS, ZFS sets uarch automatically whenever a file is
updated. The test must explicitly clear uarch to be portable across
filesystems. Also, it doesn't need to run as root.

PR:		215179
MFC after:	4 weeks
Sponsored by:	Spectra Logic Corp
Differential Revision:	https://reviews.freebsd.org/D8741

bin/ls/tests/ls_tests.sh

@@ -697,7 +697,6 @@ atf_test_case o_flag
 o_flag_head()
 {
 	atf_set "descr" "Verify that the output from ls -o prints out the chflag values or '-' if none are set"
-	atf_set "require.user" "root"
 }
 
 o_flag_body()
@@ -711,6 +710,7 @@ o_flag_body()
 	atf_check -e ignore -o empty -s exit:0 dd if=/dev/zero of=b.file \
 	    bs=$size count=1
 	atf_check -e empty -o empty -s exit:0 chflags uarch a.file
+	atf_check -e empty -o empty -s exit:0 chflags 0 b.file
 
 	atf_check -e empty -o match:"[[:space:]]+uarch[[:space:]]$size+.+a\\.file" \
 	    -s exit:0 ls -lo a.file