In compressed tiff files with RowsPerStrip > 1, TIFFReadScanline does
not support readom access that reading scan lines in arbitrary order.
This fixes that issue. In such cases, we read the initial scan lines and
discard them before reading the scan lines of interest. This also
requires that we read the file in row order in the file (rather than the
output image).

Test added in parent commit demonstrates the issue. This commit fixes
that issue.