Add support for ArcSDE implicit rowid column (shape.fid)

[aalbarello]

SDE layers can still have a valid rowid column (primary key) for use with the SE_stream_fetch_row function even when there is none registered for the table. It's a virtual field whose name can be obtained by calling the SE_layer_shape_attribute_name function with the SE_SHAPE_ATTRIBUTE_FID argument. The field can then be requested like any other column when retrieving records.

The supplied patch (against trunk r10438) adds this functionality to the SDE driver.