[llvm] llvm-reduce: Fix taking wrong error before exit (PR #135020)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `lldb-x86_64-debian` running on `lldb-x86_64-debian` while building `llvm` at step 6 "test".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/162/builds/19859

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

```
Step 6 (test) failure: build (failure)
...
PASS: lldb-api :: functionalities/breakpoint/step_over_breakpoint/TestStepOverBreakpoint.py (321 of 2824)
PASS: lldb-api :: functionalities/thread/thread_exit/TestThreadExit.py (322 of 2824)
PASS: lldb-api :: functionalities/data-formatter/special-chars/TestSummaryStringSpecialChars.py (323 of 2824)
PASS: lldb-api :: commands/frame/var/TestFrameVar.py (324 of 2824)
PASS: lldb-api :: functionalities/data-formatter/data-formatter-stl/libstdcpp/vbool/TestDataFormatterStdVBool.py (325 of 2824)
PASS: lldb-api :: lang/cpp/thunk/TestThunk.py (326 of 2824)
PASS: lldb-api :: functionalities/data-formatter/data-formatter-skip-summary/TestDataFormatterSkipSummary.py (327 of 2824)
PASS: lldb-api :: commands/expression/call-function/TestCallStopAndContinue.py (328 of 2824)
PASS: lldb-api :: commands/target/stop-hooks/TestStopHookScripted.py (329 of 2824)
UNRESOLVED: lldb-api :: driver/batch_mode/TestBatchMode.py (330 of 2824)
******************** TEST 'lldb-api :: driver/batch_mode/TestBatchMode.py' FAILED ********************
Script:
--
/usr/bin/python3 /home/worker/2.0.1/lldb-x86_64-debian/llvm-project/lldb/test/API/dotest.py -u CXXFLAGS -u CFLAGS --env LLVM_LIBS_DIR=/home/worker/2.0.1/lldb-x86_64-debian/build/./lib --env LLVM_INCLUDE_DIR=/home/worker/2.0.1/lldb-x86_64-debian/build/include --env LLVM_TOOLS_DIR=/home/worker/2.0.1/lldb-x86_64-debian/build/./bin --arch x86_64 --build-dir /home/worker/2.0.1/lldb-x86_64-debian/build/lldb-test-build.noindex --lldb-module-cache-dir /home/worker/2.0.1/lldb-x86_64-debian/build/lldb-test-build.noindex/module-cache-lldb/lldb-api --clang-module-cache-dir /home/worker/2.0.1/lldb-x86_64-debian/build/lldb-test-build.noindex/module-cache-clang/lldb-api --executable /home/worker/2.0.1/lldb-x86_64-debian/build/./bin/lldb --compiler /home/worker/2.0.1/lldb-x86_64-debian/build/./bin/clang --dsymutil /home/worker/2.0.1/lldb-x86_64-debian/build/./bin/dsymutil --make /usr/bin/gmake --llvm-tools-dir /home/worker/2.0.1/lldb-x86_64-debian/build/./bin --lldb-obj-root /home/worker/2.0.1/lldb-x86_64-debian/build/tools/lldb --lldb-libs-dir /home/worker/2.0.1/lldb-x86_64-debian/build/./lib -t /home/worker/2.0.1/lldb-x86_64-debian/llvm-project/lldb/test/API/driver/batch_mode -p TestBatchMode.py
--
Exit Code: 1

Command Output (stdout):
--
lldb version 21.0.0git (https://github.com/llvm/llvm-project.git revision 1e9f46c1b34cce7df4f2b4c392ccb0a540d7a6a6)
  clang revision 1e9f46c1b34cce7df4f2b4c392ccb0a540d7a6a6
  llvm revision 1e9f46c1b34cce7df4f2b4c392ccb0a540d7a6a6
78
(lldb) settings clear -all
7
                                                                                8(lldb) settings set symbols.enable-external-lookup false
(lldb) settings set target.inherit-tcc true
(lldb) settings set target.disable-aslr false
(lldb) settings set target.detach-on-error false
(lldb) settings set target.auto-apply-fixits false
(lldb) settings set plugin.process.gdb-remote.packet-timeout 60
(lldb) settings set symbols.clang-modules-cache-path "/home/worker/2.0.1/lldb-x86_64-debian/build/lldb-test-build.noindex/module-cache-lldb/lldb-api"
(lldb) settings set use-color false
(lldb) settings set show-statusline false
78(lldb) target create "/home/worker/2.0.1/lldb-x86_64-debian/build/lldb-test-build.noindex/driver/batch_mode/TestBatchMode.test_batch_mode_attach_exit/a.out"
Current executable set to '/home/worker/2.0.1/lldb-x86_64-debian/build/lldb-test-build.noindex/driver/batch_mode/TestBatchMode.test_batch_mode_attach_exit/a.out' (x86_64).
(lldb) process attach -p 1419881
Process 1419881 stopped
* thread #1, name = 'a.out', stop reason = signal SIGSTOP
    frame #0: 0x00007f798deee443 libc.so.6`clock_nanosleep + 35
libc.so.6`clock_nanosleep:
->  0x7f798deee443 <+35>: negl   %eax
    0x7f798deee445 <+37>: retq   
    0x7f798deee446 <+38>: nopw   %cs:(%rax,%rax)
    0x7f798deee450 <+48>: subq   $0x28, %rsp
(lldb) breakpoint set --file 'main.c' -p 'Stop here to unset keep_waiting' -N keep_waiting
Breakpoint 1: where = a.out`main + 221 at main.c:29:13, address = 0x000055a5756e525d
(lldb) continue
Process 1419881 resuming

```

</details>

https://github.com/llvm/llvm-project/pull/135020