Avoid useless creation of an array in #getColumnSpan(Mapping).

The method AbstractStandardBasicType#getColumnSpan(Mapping) returns always the length of the array returned by the method AbstractStandardBasicType#sqlTypes(Mapping). But the size of the returned array is a constant value. The method #sqlTypes(Mapping) is final and returns always an array of the size 1. Changing the #getColumnSpan(Mapping)-method to return the constant value of 1 should avoid useless creation of an array and therefore reduce the garbage produced by Hibernate.