[clang] SyntaxWarning: invalid escape sequence '\s' with Python3.12 (#78036)

llvm-project/clang/tools/libclang/linker-script-to-export-list.py:9: SyntaxWarning: invalid escape sequence '\s'
  m = re.search("^\s+(clang_[^;]+)", line)

Co-authored-by: cor3ntin <corentinjabot@gmail.com>