[clang] Multivalue+SIMD= Compiler crash

Stack dump:
```
0. Program arguments: /data/data/com.termux/files/usr/opt/emscripten-llvm/bin/clang -target wasm32-unknown-emscripten -fignore-exceptions --sysroot=/data/data/com.termux/files/usr/opt/emscripten/cache/sysroot -DEMSCRIPTEN -D__SSE__=1 -D__SSE2__=1 -Xclang -iwithsysroot/include/fakesdl -Xclang -iwithsysroot/include/compat -std=c++17 -O3 -flto -fno-builtin -msimd128 -mmultivalue -I../include -I../test -Xclang -target-abi -Xclang experimental-mv -msimd128 -mmultivalue -Xclang -target-abi -Xclang experimental-mv -c test_complex_exponential.cpp -o /data/data/com.termux/files/usr/tmp/emscripten_temp_l07fr00o/test_complex_exponential.o
1. parser at end of file
2. Per-file LLVM IR generation
3. /data/data/com.termux/files/usr/opt/emscripten/cache/sysroot/include/c++/v1/complex:816:1: Generating code for declaration 'std::operator/'
clang: error: clang frontend command failed with exit code 134 (use -v to see invocation)
clang version 22.0.0git
Target: wasm32-unknown-emscripten
Thread model: posix
InstalledDir: /data/data/com.termux/files/usr/opt/emscripten-llvm/bin
Build config: +assertions
```

[test_complex_exponential-166900.cpp](https://github.com/user-attachments/files/24828797/test_complex_exponential-166900.cpp)
[test_complex_exponential-166900.sh](https://github.com/user-attachments/files/24828798/test_complex_exponential-166900.sh)

Start by running test_complex_exponential-166900.sh with test_complex_exponential-166900.cpp using the command and wasm32 Emscripten options in the report. Read the compiler stack around std::operator/ in the C++ v1 complex header at line 816, then trace the SIMD and multivalue code-generation path. Done means the reproducer compiles without the clang frontend crash.

Written by the indexing model from the issue text.