[llvm] [NFC] LLVM reduce: remove unused variable (PR #133584)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-x86_64-debian-fast` running on `gribozavr4` while building `llvm` at step 5 "build-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/56/builds/22192

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

```
Step 5 (build-unified-tree) failure: build (failure)
...
73.428 [26/27/6148] Linking CXX executable bin/clangd-indexer
73.728 [26/26/6149] Linking CXX executable bin/clang-extdef-mapping
74.203 [26/25/6150] Linking CXX executable bin/clangd
74.398 [26/24/6151] Linking CXX executable bin/bugpoint
74.432 [25/24/6152] Linking CXX executable bin/clangd-fuzzer
74.443 [25/23/6153] Building CXX object tools/bugpoint-passes/CMakeFiles/BugpointPasses.dir/TestPasses.cpp.o
74.452 [24/23/6154] Linking CXX executable bin/llvm-dwp
74.513 [24/22/6155] Linking CXX shared module lib/BugpointPasses.so
74.690 [24/21/6156] Linking CXX executable bin/llvm-gsymutil
74.788 [24/20/6157] Building CXX object tools/llvm-reduce/CMakeFiles/llvm-reduce.dir/deltas/ReduceOperandsToArgs.cpp.o
FAILED: tools/llvm-reduce/CMakeFiles/llvm-reduce.dir/deltas/ReduceOperandsToArgs.cpp.o 
CCACHE_CPP2=yes CCACHE_HASHDIR=yes /usr/bin/ccache /usr/bin/clang++ -DGTEST_HAS_RTTI=0 -DLLVM_BUILD_STATIC -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/b/1/clang-x86_64-debian-fast/llvm.obj/tools/llvm-reduce -I/b/1/clang-x86_64-debian-fast/llvm.src/llvm/tools/llvm-reduce -I/b/1/clang-x86_64-debian-fast/llvm.obj/include -I/b/1/clang-x86_64-debian-fast/llvm.src/llvm/include -std=c++11 -Wdocumentation -Wno-documentation-deprecated-sync -fPIC -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG  -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -std=c++17 -MD -MT tools/llvm-reduce/CMakeFiles/llvm-reduce.dir/deltas/ReduceOperandsToArgs.cpp.o -MF tools/llvm-reduce/CMakeFiles/llvm-reduce.dir/deltas/ReduceOperandsToArgs.cpp.o.d -o tools/llvm-reduce/CMakeFiles/llvm-reduce.dir/deltas/ReduceOperandsToArgs.cpp.o -c /b/1/clang-x86_64-debian-fast/llvm.src/llvm/tools/llvm-reduce/deltas/ReduceOperandsToArgs.cpp
/b/1/clang-x86_64-debian-fast/llvm.src/llvm/tools/llvm-reduce/deltas/ReduceOperandsToArgs.cpp:112:13: error: 'setFastMathFlags' is a private member of 'llvm::FPMathOperator'
      FPOp->setFastMathFlags(CI->getFastMathFlags());
            ^
/b/1/clang-x86_64-debian-fast/llvm.src/llvm/include/llvm/IR/Operator.h:264:8: note: declared private here
  void setFastMathFlags(FastMathFlags FMF) {
       ^
1 error generated.
74.907 [24/19/6158] Linking CXX executable bin/llvm-split
75.016 [24/18/6159] Linking CXX executable bin/llvm-c-test
75.103 [24/17/6160] Linking CXX executable bin/llvm-lto
75.340 [24/16/6161] Linking CXX executable bin/dsymutil
75.451 [24/15/6162] Linking CXX executable bin/clang-tidy
75.464 [24/14/6163] Linking CXX executable bin/llvm-lto2
75.522 [24/13/6164] Linking CXX executable bin/llvm-isel-fuzzer
75.556 [24/12/6165] Linking CXX executable bin/llc
75.900 [24/11/6166] Linking CXX executable bin/opt
75.929 [24/10/6167] Linking CXX executable bin/llvm-opt-fuzzer
76.073 [24/9/6168] Linking CXX executable bin/llvm-dwarfutil
76.369 [24/8/6169] Linking CXX executable bin/clang-nvlink-wrapper
76.393 [24/7/6170] Linking CXX shared library lib/libLTO.so.21.0git
76.445 [24/6/6171] Linking CXX executable bin/clang-linker-wrapper
76.782 [24/5/6172] Linking CXX shared library lib/libclang-cpp.so.21.0git
77.193 [24/4/6173] Linking CXX executable bin/clang-check
77.836 [24/3/6174] Linking CXX shared library lib/libclang.so.21.0.0git
78.398 [24/2/6175] Linking CXX executable bin/clang-repl
79.054 [24/1/6176] Linking CXX executable bin/clang-21
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/133584