[NFC][sanitizer] Link LLVMOption and allow strtof in internal symbolizer (#228490)

Commit f6c78b8262f4 (#228321) moved MC command-line options into
`MCCLOptions.cpp` and added an `LLVMOption` dependency to `LLVMMC`.
Because
`MCAsmInfo.cpp` references `MCCLOptions::Global`, `MCCLOptions.cpp` and
its
generated option parser (which also calls `strtof` via `llvm::to_float`)
are
pulled into the internal symbolizer link.

Add `LLVMOption` to `build_symbolizer.sh` and `strtof U` to
`global_symbols.txt` so internal symbolizer builds and symbol
verification
succeed.

Fixes: https://lab.llvm.org/buildbot/#/builders/66/builds/38119

Assisted-by: Gemini
GitOrigin-RevId: 7232ec8b92e50c4a1ac6a268a7ce8384941104ec