transcoder_interal: Fix CP1252-encoded char in a comment

[akien-mga]

Would appear in nano as an invalid UTF-8 char:

And <96> in the git diff after removing it, which seems to be the code for – in CP1252.

We found this because Emscripten choked when parsing this file from Windows:

Traceback (most recent call last):
  File "C:\repos\emsdk\upstream\emscripten\em++.py", line 16, in <module>
    sys.exit(emcc.main(sys.argv))
             ~~~~~~~~~^^^^^^^^^^
  File "C:\Users\name\scoop\apps\python\current\Lib\contextlib.py", line 85, in inner
    return func(*args, **kwds)
  File "C:\repos\emsdk\upstream\emscripten\emcc.py", line 357, in main
    return link.run(options, linker_args)
           ~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^
  File "C:\repos\emsdk\upstream\emscripten\tools\link.py", line 3196, in run
    phase_post_link(options, wasm_target, wasm_target, target, js_syms, base_metadata)
    ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\name\scoop\apps\python\current\Lib\contextlib.py", line 85, in inner
    return func(*args, **kwds)
  File "C:\repos\emsdk\upstream\emscripten\tools\link.py", line 1921, in phase_post_link
    metadata = phase_emscript(in_wasm, wasm_target, js_syms, base_metadata)
  File "C:\Users\name\scoop\apps\python\current\Lib\contextlib.py", line 85, in inner
    return func(*args, **kwds)
  File "C:\repos\emsdk\upstream\emscripten\tools\link.py", line 1961, in phase_emscript
    metadata = emscripten.emscript(in_wasm, wasm_target, final_js, js_syms, base_metadata=base_metadata)
  File "C:\repos\emsdk\upstream\emscripten\tools\emscripten.py", line 366, in emscript
    metadata = finalize_wasm(in_wasm, out_wasm, js_syms)
  File "C:\repos\emsdk\upstream\emscripten\tools\emscripten.py", line 554, in finalize_wasm
    building.emit_wasm_source_map(infile, outfile + '.map', outfile)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\repos\emsdk\upstream\emscripten\tools\building.py", line 1189, in emit_wasm_source_map
    rtn = wasm_sourcemap.main(sourcemap_cmd)
  File "C:\repos\emsdk\upstream\emscripten\tools\wasm-sourcemap.py", line 614, in main
    map = build_sourcemap(entries, func_ranges, code_section_offset, options)
  File "C:\repos\emsdk\upstream\emscripten\tools\wasm-sourcemap.py", line 571, in build_sourcemap
    source_content = utils.read_file(load_name)
  File "C:\repos\emsdk\upstream\emscripten\tools\utils.py", line 172, in read_file
    return fh.read()
           ~~~~~~~^^
  File "<frozen codecs>", line 325, in decode
UnicodeDecodeError: 'utf-8' codec can't decode byte 0x96 in position 47339: invalid start byte