[llvm] [SmallPtrSet] Remove SmallArray member (NFC) (PR #118099)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-aarch64-sve-vls-2stage` running on `linaro-g3-04` while building `llvm` at step 11 "build stage 2".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/4/builds/3923

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

```
Step 11 (build stage 2) failure: 'ninja' (failure)
...
[7922/8767] Building CXX object tools/flang/lib/Lower/CMakeFiles/FortranLower.dir/ComponentPath.cpp.o
[7923/8767] Building CXX object tools/flang/lib/Evaluate/CMakeFiles/FortranEvaluate.dir/initial-image.cpp.o
[7924/8767] Building CXX object tools/flang/lib/Evaluate/CMakeFiles/FortranEvaluate.dir/type.cpp.o
[7925/8767] Building CXX object tools/flang/lib/Evaluate/CMakeFiles/FortranEvaluate.dir/expression.cpp.o
[7926/8767] Building CXX object tools/flang/lib/Evaluate/CMakeFiles/FortranEvaluate.dir/variable.cpp.o
[7927/8767] Building CXX object tools/flang/lib/Evaluate/CMakeFiles/FortranEvaluate.dir/intrinsics.cpp.o
[7928/8767] Building CXX object tools/flang/lib/Evaluate/CMakeFiles/FortranEvaluate.dir/characteristics.cpp.o
[7929/8767] Building CXX object tools/flang/lib/Evaluate/CMakeFiles/FortranEvaluate.dir/intrinsics-library.cpp.o
[7930/8767] Building CXX object tools/flang/lib/Parser/CMakeFiles/FortranParser.dir/executable-parsers.cpp.o
[7931/8767] Building CXX object tools/flang/lib/Evaluate/CMakeFiles/FortranEvaluate.dir/fold.cpp.o
command timed out: 1200 seconds without output running [b'ninja'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=3076.441406

```

</details>

https://github.com/llvm/llvm-project/pull/118099