Destructor of GML data source does not flush non seekable output file
ogrgmldatasource.cpp:144 calls VSIFCloseL for the output. However, VSIFCloseL does not flush the file. Thus, even though the GML data source object may be gone, its output may still be pending. This is a problem for example in the web environment, where one needs control over output.
In my case I'm using /vsistdout/. Maybe Flush() should be called in the Close method of VSIStdoutHandle if not in VSIFCloseL.