fb6f1bde00
Update the Itanium demangler to recognize and strip `__alloc_token_` prefixes introduced by AllocToken instrumentation [1]. This ensures that instrumented allocation functions (e.g., `__alloc_token__Znwm`) demangle back to their original source-level names (e.g., `operator new(unsigned long)`) with a suffix `(.alloc_token)` indicating their non-standard origin. Since AllocToken is intended to be transparent to users who continue to use `operator new` as before, the demangled name should reflect this reality instead of confusing users with internal instrumentation names in stack traces or symbolization output. Synchronize changes across llvm and libcxxabi copies. [1] https://clang.llvm.org/docs/AllocToken.html Original RFC: https://discourse.llvm.org/t/rfc-a-framework-for-allocator-partitioning-hints/87434