add basic 16bit-cielab support
just a copy of putcontig8bitCIELab that reads 16bit vals but divide by 256 before passing to TIFFCIELabToXYZ
motivation: https://bugs.documentfoundation.org/show_bug.cgi?id=131199 the "clavijo16bitlab.tiff" example where tiffinfo says:
Image Width: 2601 Image Length: 3503 Resolution: 96, 96 pixels/inch Bits/Sample: 16 Compression Scheme: AdobeDeflate Photometric Interpretation: CIE Lab* Orientation: row 0 top, col 0 lhs Samples/Pixel: 3 Rows/Strip: 1 Planar Configuration: single image plane DateTime: 2020:03:07 10:20:42