fix getJpegInfo to skip DHT marker
#3854
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Fixes #3318.
getJpegInfonow skips the DHT marker (0xc4) because that marker is not a SOF (start of frame) marker and therefore the segment to follow does not have the size information.To add to insight to this fix, the original getJpegInfo sites http://www.64lines.com/jpeg-width-height which itself sites a reference for header info: JPEG Header Information
As you can see here, Define Huffman table marker (FFC4), 0xC4 is a marker for the Huffman table.
My fix skips 0xC4 and adjusts the remaining Start of frame (SOFn) markers to be correct.