[llvm] SLPVectorizer: strip bad FIXME (NFC) (PR #122888)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `openmp-s390x-linux` running on `systemz-1` while building `llvm` at step 6 "test-openmp".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/88/builds/6763

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-openmp) failure: test (failure)
******************** TEST 'libomp :: tasking/omp_task_red_taskloop.c' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 1
/home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/./bin/clang -fopenmp   -I /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/runtimes/runtimes-bins/openmp/runtime/src -I /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.src/openmp/runtime/test -L /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/runtimes/runtimes-bins/openmp/runtime/src  -fno-omit-frame-pointer -mbackchain -I /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.src/openmp/runtime/test/ompt /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.src/openmp/runtime/test/tasking/omp_task_red_taskloop.c -o /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/runtimes/runtimes-bins/openmp/runtime/test/tasking/Output/omp_task_red_taskloop.c.tmp -lm -latomic && /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/runtimes/runtimes-bins/openmp/runtime/test/tasking/Output/omp_task_red_taskloop.c.tmp
# executed command: /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/./bin/clang -fopenmp -I /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/runtimes/runtimes-bins/openmp/runtime/src -I /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.src/openmp/runtime/test -L /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/runtimes/runtimes-bins/openmp/runtime/src -fno-omit-frame-pointer -mbackchain -I /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.src/openmp/runtime/test/ompt /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.src/openmp/runtime/test/tasking/omp_task_red_taskloop.c -o /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/runtimes/runtimes-bins/openmp/runtime/test/tasking/Output/omp_task_red_taskloop.c.tmp -lm -latomic
# executed command: /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/runtimes/runtimes-bins/openmp/runtime/test/tasking/Output/omp_task_red_taskloop.c.tmp
# .---command stdout------------
# | executing task (0, 0), th 1 (gen by th 0)
# | executing task (0, 1), th 0 (gen by th 0)
# | th 0 passed bar0
# | executing task (3, 1), th 0 (gen by th 0)
# | executing task (3, 0), th 0 (gen by th 0)
# | th 0 (gen by th 0) passed bar3 in taskloop
# | executing task (1, 1), th 1 (gen by th 1)
# | executing task (2, 1), th 0 (gen by th 0)
# | executing task (1, 0), th 1 (gen by th 1)
# | executing task (2, 0), th 0 (gen by th 0)
# | th 0 (gen by th 0) passed bar2 in taskloop
# | th 1 (gen by th 0) passed bar1 in taskloop
# | error r = 25 (!= 30)
# `-----------------------------
# error: command failed with exit status: 1

--

********************


```

</details>

https://github.com/llvm/llvm-project/pull/122888