band.ComputeStatistics() fails with callback arguments

[Sam Gillingham]

In GDAL 2.2.0, the following code now fails:

def GDALProgressFunc(value, string, extra):
    print(value)

ds = gdal.Open(sys.argv[1], gdal.GA_Update)
band = ds.GetRasterBand(1)
band.ComputeStatistics(False, GDALProgressFunc, 0)

This used to work in 2.1.3. Runs fine if you remove the last 2 arguments. I suspect this is a result of the new typemap for this introduced in [36845] which doesn't mention these extra parameters, but I could well be wrong.

[Even Rouault]

In 39125:

Python bindings: fix 2.2 regression preventing use of callback function in Band.ComputeStatistics() (fixes #6927)

[Even Rouault]

In 39126:

Python bindings: fix 2.2 regression preventing use of callback function in Band.ComputeStatistics() (fixes #6927)