The JPEG reader attempts to skip scanlines when a Y subsampling factor
greater than 1 is used. This can result in an attempt to read past the end
of the image, which results in a warning message being printed on stderr
by the IJG library.

  The fix is to skip the minimum of 'stepY - 1' and 'scanlineLimit - cinfo->output_scanline' instead of always skipping 'stepY - 1' in the
native routine for JPEGImageReader.readImage.

  The existing regression test in test/javax/imageio/IRPTest.java may
be used as a test for this bug; the message 'Application transferred too
many scanlines' should not appear.