`-flto` + `-fwasm-exceptions` flags together break the compiler

Here's a minimal reproducer:

$ echo 'int main(){}' >test.c
$ wasi-sdk-33.0-x86_64-linux/bin/clang --target=wasm32-wasip1 --sysroot wasi-sdk-33.0-x86_64-linux/share/wasi-sysroot -fwasm-exceptions -mllvm -wasm-use-legacy-eh=false -flto -lunwind test.c
wasm-ld: error: symbol type mismatch: __cpp_exception
>>> defined as WASM_SYMBOL_TYPE_FUNCTION in .../wasi-sdk-33.0-x86_64-linux/share/wasi-sysroot/lib/wasm32-wasip1/eh/llvm-lto/22.1.0-wasi-sdk/libunwind.a(Unwind-wasm.c.o)
>>> defined as WASM_SYMBOL_TYPE_TAG in a.out.lto.o
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Here's the error I'm getting from CMake during compiler detection:

-- Check for working C compiler: /usr/bin/ccache
-- Check for working C compiler: /usr/bin/ccache - broken
CMake Error at /usr/share/cmake-3.31/Modules/CMakeTestCCompiler.cmake:67 (message):
  The C compiler

    "/usr/bin/ccache"

  is not able to compile a simple test program.

  It fails with the following output:

    Change Dir: '/home/whitequark/Projects/yowasp/nextpnr/prjtrellis-build/CMakeFiles/CMakeScratch/TryCompile-axg3T6'
    
    Run Build Command(s): /usr/bin/cmake -E env VERBOSE=1 /usr/bin/gmake -f Makefile cmTC_31eb1/fast
    /usr/bin/gmake  -f CMakeFiles/cmTC_31eb1.dir/build.make CMakeFiles/cmTC_31eb1.dir/build
    gmake[1]: Entering directory '/home/whitequark/Projects/yowasp/nextpnr/prjtrellis-build/CMakeFiles/CMakeScratch/TryCompile-axg3T6'
    Building C object CMakeFiles/cmTC_31eb1.dir/testCCompiler.c.obj
    /usr/bin/ccache /home/whitequark/Projects/yowasp/nextpnr/wasi-sdk-33.0-x86_64-linux/bin/clang --target=wasm32-wasip1   --sysroot /home/whitequark/Projects/yowasp/nextpnr/wasi-sdk-33.0-x86_64-linux/share/wasi-sysroot -fwasm-exceptions -mllvm -wasm-use-legacy-eh=false -flto  -MD -MT CMakeFiles/cmTC_31eb1.dir/testCCompiler.c.obj -MF CMakeFiles/cmTC_31eb1.dir/testCCompiler.c.obj.d -o CMakeFiles/cmTC_31eb1.dir/testCCompiler.c.obj -c /home/whitequark/Projects/yowasp/nextpnr/prjtrellis-build/CMakeFiles/CMakeScratch/TryCompile-axg3T6/testCCompiler.c
    Linking C executable cmTC_31eb1
    /usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_31eb1.dir/link.txt --verbose=1
    clang: warning: argument unused during compilation: '-mllvm -wasm-use-legacy-eh=false' [-Wunused-command-line-argument]
    wasm-ld: error: symbol type mismatch: __cpp_exception
    >>> defined as WASM_SYMBOL_TYPE_FUNCTION in /home/whitequark/Projects/yowasp/nextpnr/wasi-sdk-33.0-x86_64-linux/share/wasi-sysroot/lib/wasm32-wasip1/eh/llvm-lto/22.1.0-wasi-sdk/libunwind.a(Unwind-wasm.c.o)
    >>> defined as WASM_SYMBOL_TYPE_TAG in cmTC_31eb1.lto.o
    clang: error: linker command failed with exit code 1 (use -v to see invocation)
    /usr/bin/ccache /home/whitequark/Projects/yowasp/nextpnr/wasi-sdk-33.0-x86_64-linux/bin/clang --target=wasm32-wasip1 --sysroot /home/whitequark/Projects/yowasp/nextpnr/wasi-sdk-33.0-x86_64-linux/share/wasi-sysroot -fwasm-exceptions -mllvm -wasm-use-legacy-eh=false -flto  -lunwind -Wl,--strip-all  CMakeFiles/cmTC_31eb1.dir/testCCompiler.c.obj -o cmTC_31eb1
    gmake[1]: *** [CMakeFiles/cmTC_31eb1.dir/build.make:103: cmTC_31eb1] Error 1
    gmake[1]: Leaving directory '/home/whitequark/Projects/yowasp/nextpnr/prjtrellis-build/CMakeFiles/CMakeScratch/TryCompile-axg3T6'
    gmake: *** [Makefile:134: cmTC_31eb1/fast] Error 2

Start with the minimal test.c reproducer using wasi-sdk-33.0-x86_64-linux/bin/clang and compare builds with -fwasm-exceptions, -mllvm -wasm-use-legacy-eh=false, and -flto. Inspect the CMake compiler-detection invocation in CMakeTestCCompiler.cmake and the reported __cpp_exception mismatch between libunwind.a and the LTO object. Done means the flag combination links successfully without the wasm-ld symbol type mismatch.