Add basic tests for chflags(1), ctfconvert(1), fold(1) and rs(1)

[shivansh]

Summary

Tests generated via: https://github.com/shivansh/smoketestsuite/
Reference: r323275

[asomers]

It is not ok to impose restrictions on how somebody invokes "kyua test". If some of these tests need to close stdin, then you'll have to do that from within the testcase body.

[shivansh]

Close stdin where required in the tests

[asomers]

Can you please add .include <src.opts.mk> to every Makefile that references MK_TESTS?

[shivansh]

Add .include <src.opts.mk> to every Makefile that references MK_TESTS

[asomers]

I just realized that this review is out of date. chflags' tests were already submitted in r323275 on 7-sep. Could you please update the review to either remove chflags or, if the chflags tests are changing, rebase the changes on top of head?

[shivansh]

Remove test for chflags(1) -- already submitted in r323275.

PS. My apologies for the delay, just finished with my final exams today!

[asomers]

LGTM.