Properly track column numbers in erl_scan

This is a partial revert of 05c4d31b2c5c5f6ade7d91b55c598fe7fa58e509 in
which a new macro `?STR()` was introduced. This macro shouldn't be used in
scan_number/6 and scan_based_int/6 because the length of the string is
needed when computing column numbers through tok3/8.