[PATCH] debug: test for more required cacellation points (bug 29274)

[Adhemerval Zanella]

> On 23 Jun 2022, at 11:13, Andreas Schwab <schwab@suse.de> wrote:
> 
> It doesn't work.  pread absolutely requires a seekable file, but I don't
> know how to create a seekable *and* blocking file.

sysdeps/pthread/tst-cancel4.c check if pread works with a pending
cancelation.  Maybe add the same strategy on this new test.

> 
> -- 
> Andreas Schwab, SUSE Labs, schwab@suse.de
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> "And now for something completely different."