Previously, the into-type would take the blob object's LOB locator
object and bind that in the query. That works as long as there is only a
single Blob object being fetched from the database. However, if multiple
values are fetched consecutively, there would only be a single locator
object involved. In the best case, this leads to every new fetch
overriding the previous result and in the worst case, that previous
result has been turned into an independent blob object that has gone out
of scope, which leads to freeing of this shared locator.

With this commit, the into-type object will create its own locator
object and use that. When assigning the fetched result to a blob object,
the locator is copied such that the into-type and the blob keep
independent locator objects, i.e. the locator is no longer shared.