[llvm] [TableGen] Avoid assignmentInAssert warning (PR #139715)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-sie-win` running on `sie-win-worker` while building `llvm` at step 7 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/46/builds/16703

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

```
Step 7 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: TableGen/GlobalISelCombinerEmitter/match-table-imms.td' FAILED ********************
Exit Code: 2

Command Output (stdout):
--
# RUN: at line 1
z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-tblgen.exe -I Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm\test\TableGen\GlobalISelCombinerEmitter/../../../include -gen-global-isel-combiner      -combiners=MyCombiner Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm\test\TableGen\GlobalISelCombinerEmitter\match-table-imms.td |  z:\b\llvm-clang-x86_64-sie-win\build\bin\filecheck.exe Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm\test\TableGen\GlobalISelCombinerEmitter\match-table-imms.td
# executed command: 'z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-tblgen.exe' -I 'Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm\test\TableGen\GlobalISelCombinerEmitter/../../../include' -gen-global-isel-combiner -combiners=MyCombiner 'Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm\test\TableGen\GlobalISelCombinerEmitter\match-table-imms.td'
# .---command stderr------------
# | Assertion failed: ExpectedID == ID && "combine rules are not ordered!", file Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm\utils\TableGen\GlobalISelCombinerEmitter.cpp, line 2615
# | PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
# | Stack dump:
# | 0.	Program arguments: z:\\b\\llvm-clang-x86_64-sie-win\\build\\bin\\llvm-tblgen.exe -I Z:\\b\\llvm-clang-x86_64-sie-win\\llvm-project\\llvm\\test\\TableGen\\GlobalISelCombinerEmitter/../../../include -gen-global-isel-combiner -combiners=MyCombiner Z:\\b\\llvm-clang-x86_64-sie-win\\llvm-project\\llvm\\test\\TableGen\\GlobalISelCombinerEmitter\\match-table-imms.td
# | Exception Code: 0x80000003
# |  #0 0x00007ff69081ae05 (z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-tblgen.exe+0x2eae05)
# |  #1 0x00007ff8bb44d88d (C:\Windows\System32\ucrtbase.dll+0x6d88d)
# |  #2 0x00007ff8bb44e761 (C:\Windows\System32\ucrtbase.dll+0x6e761)
# |  #3 0x00007ff8bb4500c1 (C:\Windows\System32\ucrtbase.dll+0x700c1)
# |  #4 0x00007ff8bb4503f1 (C:\Windows\System32\ucrtbase.dll+0x703f1)
# |  #5 0x00007ff690709f09 (z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-tblgen.exe+0x1d9f09)
# |  #6 0x00007ff6905a3c74 (z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-tblgen.exe+0x73c74)
# |  #7 0x00007ff69072e4ab (z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-tblgen.exe+0x1fe4ab)
# |  #8 0x00007ff69071a8b1 (z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-tblgen.exe+0x1ea8b1)
# |  #9 0x00007ff69085206e (z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-tblgen.exe+0x32206e)
# | #10 0x00007ff690855d8a (z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-tblgen.exe+0x325d8a)
# | #11 0x00007ff690571a65 (z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-tblgen.exe+0x41a65)
# | #12 0x00007ff690880490 (z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-tblgen.exe+0x350490)
# | #13 0x00007ff8bef67ac4 (C:\Windows\System32\KERNEL32.DLL+0x17ac4)
# | #14 0x00007ff8bf1ba8c1 (C:\Windows\SYSTEM32\ntdll.dll+0x5a8c1)
# `-----------------------------
# error: command failed with exit status: 0x80000003
# executed command: 'z:\b\llvm-clang-x86_64-sie-win\build\bin\filecheck.exe' 'Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm\test\TableGen\GlobalISelCombinerEmitter\match-table-imms.td'
# .---command stderr------------
# | FileCheck error: '<stdin>' is empty.
# | FileCheck command line:  z:\b\llvm-clang-x86_64-sie-win\build\bin\filecheck.exe Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm\test\TableGen\GlobalISelCombinerEmitter\match-table-imms.td
# `-----------------------------
# error: command failed with exit status: 2

--

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


```

</details>

https://github.com/llvm/llvm-project/pull/139715