Unify emit_logger_call and emit_dynamic_logger_call.

This allows got Logger in calls like ale:debug(Logger, ...) to be an
arbitrary expression (not just an atom).

Change-Id: Ib515732491acb9c8ccbe85342bdebfc50d2b05ae
Reviewed-on: http://review.couchbase.org/37525
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>