Convert source file to UTF-8 in order to compile with Erlang R17

This commit replaces byte "f6" with bytes "c3 b6".

The snapshot of R17 pre-release used for compiling is 039ea3a.

The compilation succeeds also with R13B04 so hopefully this should not
introduce regressions for versions of Erlang older than R17.

See also http://erlang.org/doc/apps/stdlib/unicode_usage.html