SDK should support Undefined Behavior Sanitizer

Per https://github.com/llvm/llvm-project/issues/151015#issuecomment-3130203774.

Currently it results in a linker error:

$ /opt/wasi-sdk/bin/clang -fsanitize=undefined test.c
wasm-ld: error: /tmp/test-1cf416.o: undefined symbol: __ubsan_handle_pointer_overflow
wasm-ld: error: /tmp/test-1cf416.o: undefined symbol: __ubsan_handle_type_mismatch_v1
clang: error: linker command failed with exit code 1 (use -v to see invocation)

This is because sanitizer runtimes are turned off:

https://github.com/WebAssembly/wasi-sdk/blob/d05b57d2a21229fbc1d492d204057cf4751de697/cmake/wasi-sdk-sysroot.cmake#L82

I tried turning them on and that causes a cascade of failures, not the least a bunch of fuzzer headers appearing in include-all.c; some of which don't compile and some introduce new symbols. How should I proceed? I could add them to the find command with exclusions but there's like 15 new headers.

Inspect cmake/wasi-sdk-sysroot.cmake around the sanitizer-runtime setting and review how enabling it affects include-all.c. Reproduce the issue with the shown clang -fsanitize=undefined command, then verify that the SDK links successfully without the reported UBSan symbols or header-related failures.