generic/019: don't fail if fio crashes while shutting down

generic/019: don't fail if fio crashes while shutting down

My system (Debian 12) has fio 3.33.  Once in a while, fio crashes while
shutting down after it receives a SIGBUS on account of the filesystem
going down.  This causes the test to fail with:

generic/019       - output mismatch (see /var/tmp/fstests/generic/019.out.bad)
    --- tests/generic/019.out   2024-02-28 16:20:24.130889521 -0800
    +++ /var/tmp/fstests/generic/019.out.bad    2025-01-03 15:00:35.903564431 -0800
    @@ -5,5 +5,6 @@

     Start fio..
     Force SCRATCH_DEV device failure
    +/tmp/fstests/tests/generic/019: line 112: 90841 Segmentation fault      $FIO_PROG $fio_config >> $seqres.full 2>&1
     Make SCRATCH_DEV device operable again
     Disallow global fail_make_request feature
    ...
    (Run 'diff -u /tmp/fstests/tests/generic/019.out /var/tmp/fstests/generic/019.out.bad'  to see the entire diff)

because the wait command will dutifully report fatal signals that kill
the fio process.  Unfortunately, a core dump shows that we blew up in
some library's exit handler somewhere:

(gdb) where
#0  unlink_chunk (p=p@entry=0x55b31cb9a430, av=0x7f8b4475ec60 <main_arena>) at ./malloc/malloc.c:1628
#1  0x00007f8b446222ff in _int_free (av=0x7f8b4475ec60 <main_arena>, p=0x55b31cb9a430, have_lock=<optimized out>, have_lock@entry=0) at ./malloc/malloc.c:4603
#2  0x00007f8b44624f1f in __GI___libc_free (mem=<optimized out>) at ./malloc/malloc.c:3385
#3  0x00007f8b3a71cf0e in ?? () from /lib/x86_64-linux-gnu/libtasn1.so.6
#4  0x00007f8b4426447c in ?? () from /lib/x86_64-linux-gnu/libgnutls.so.30
#5  0x00007f8b4542212a in _dl_call_fini (closure_map=closure_map@entry=0x7f8b44465620) at ./elf/dl-call_fini.c:43
#6  0x00007f8b4542581e in _dl_fini () at ./elf/dl-fini.c:114
#7  0x00007f8b445ca55d in __run_exit_handlers (status=0, listp=0x7f8b4475e820 <__exit_funcs>, run_list_atexit=run_list_atexit@entry=true, run_dtors=run_dtors@entry=true)
    at ./stdlib/exit.c:116
#8  0x00007f8b445ca69a in __GI_exit (status=<optimized out>) at ./stdlib/exit.c:146
#9  0x00007f8b445b3251 in __libc_start_call_main (main=main@entry=0x55b319278e10 <main>, argc=argc@entry=2, argv=argv@entry=0x7ffec6f8b468) at ../sysdeps/nptl/libc_start_call_main.h:74
#10 0x00007f8b445b3305 in __libc_start_main_impl (main=0x55b319278e10 <main>, argc=2, argv=0x7ffec6f8b468, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>,
    stack_end=0x7ffec6f8b458) at ../csu/libc-start.c:360
#11 0x000055b319278ed1 in _start ()

This isn't a filesystem failure, so mask this by shovelling the output
to seqres.full.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>