ptrace: fix clearing of JOBCTL_TRACED in ptrace_unfreeze_traced()

ptrace: fix clearing of JOBCTL_TRACED in ptrace_unfreeze_traced()

CI reported the following splat while running the strace testsuite:

[ 3976.640309] WARNING: CPU: 1 PID: 3570031 at kernel/ptrace.c:272 ptrace_check_attach+0x12e/0x178
[ 3976.640391] CPU: 1 PID: 3570031 Comm: strace Tainted: G           OE     5.19.0-20220624.rc3.git0.ee819a77d4e7.300.fc36.s390x #1
[ 3976.640410] Hardware name: IBM 3906 M04 704 (z/VM 7.1.0)
[ 3976.640452] Call Trace:
[ 3976.640454]  [<00000000ab4b645a>] ptrace_check_attach+0x132/0x178
[ 3976.640457] ([<00000000ab4b6450>] ptrace_check_attach+0x128/0x178)
[ 3976.640460]  [<00000000ab4b6cde>] __s390x_sys_ptrace+0x86/0x160
[ 3976.640463]  [<00000000ac03fcec>] __do_syscall+0x1d4/0x200
[ 3976.640468]  [<00000000ac04e312>] system_call+0x82/0xb0
[ 3976.640470] Last Breaking-Event-Address:
[ 3976.640471]  [<00000000ab4ea3c8>] wait_task_inactive+0x98/0x190

This is because JOBCTL_TRACED is set, but the task is not in TASK_TRACED
state. Caused by ptrace_unfreeze_traced() which does:

task->jobctl &= ~TASK_TRACED

but it should be:

task->jobctl &= ~JOBCTL_TRACED

Fixes: 31cae1eaae4f ("sched,signal,ptrace: Rework TASK_TRACED, TASK_STOPPED state")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Link: https://lkml.kernel.org/r/20220706101625.2100298-1-svens@linux.ibm.com
Link: https://lkml.kernel.org/r/YrHA5UkJLornOdCz@li-4a3a4a4c-28e5-11b2-a85c-a8d192c6f089.ibm.com
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2101641
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Alexander Gordeev <agordeev@linux.ibm.com>
Tested-by: Linus Torvalds <torvalds@linuxfoundation.org>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>