The test framework marks a test failed if it sees a "todo" on passing test.
Remove the todos on the tests that we know will pass.

--- a/tests/chown/00.t	2019-11-22 15:42:02.491358691 +0900
+++ b/tests/chown/00.t	2019-11-22 15:06:14.723357667 +0900
@@ -389,7 +389,6 @@
 		sleep 1
 		expect 0 -- chown ${n0} -1 -1
 		ctime2=`${fstest} stat ${n0} ctime`
-		todo Linux "According to POSIX: If both owner and group are -1, the times need not be updated."
 		test_check $ctime1 -eq $ctime2
 		expect 0,0 stat ${n0} uid,gid
 
@@ -398,7 +397,6 @@
 		sleep 1
 		expect 0 -- chown ${n1} -1 -1
 		ctime2=`${fstest} stat ${n1} ctime`
-		todo Linux "According to POSIX: If both owner and group are -1, the times need not be updated."
 		test_check $ctime1 -eq $ctime2
 		expect 0,0 stat ${n1} uid,gid
 		expect 0 unlink ${n1}
@@ -416,7 +414,6 @@
 	sleep 1
 	expect 0 -- lchown ${n0} -1 -1
 	ctime2=`${fstest} lstat ${n0} ctime`
-	todo Linux "According to POSIX: If both owner and group are -1, the times need not be updated."
 	test_check $ctime1 -eq $ctime2
 	expect 0,0 lstat ${n0} uid,gid