SXF: faulty destruction of the mutex

[akhliustov]

SXF datasources use shared mutex which is destroyed here: http://trac.osgeo.org/gdal/browser/trunk/gdal/ogr/ogrsf_frmts/sxf/ogrsxfdatasource.cpp#L114. It is a wrong place for destruction, because the mutex can be still in use by another datasource. A better place is in the destructor of the driver.

[bishop]

The main aim of the mutex is prevent to simultaneously access the same file from different layers. The one SXF file can have several layes, so I set SXF file handler at layer constructor. And I need to prevent the seek and read from different layers simultaneously. But each datasource have diffent file handlers (different SXF files), so there is no need in such global mutex in driver.

[akhliustov]

Well, if there should be one mutex per datasource instance, then it should be datasource member variable, not static.

[bishop]

Fixed in r27285