lcms2: Update to 2.12

lcms2: Update to 2.12

- Update lcms2 from 2.9 to 2.12
- Updated rootfile
- Changelog
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2.12 Maintenance release
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Added new build-in sigmoidal tone curve
Added XCode 12 project
Added support for multichannel input up to 15 channels
Fix LUT8 write matrix
Fix version mess on 10/11
Fix tools & samples xgetopt
Fix warnings on different function pointers
Fix matlab MEX compilation
plugin: cleanup and better SSE detection
plugin: add lab to any on float
plugin: it can now be compiled as C++
recover PDF documentation, but try to keep it under a resonable size.
Prevent a rare but possible out-of-bounds read in postscript generator
Remove unused variables
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2.11 Maintenance release
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Fixed __cpuid() on fast float plugin to allow gnu gcc
Fixed copy alpha bounds check
Fixed data race condition on contexts pool
Fixed LUT16 write matrix on multichannel V2 profiles
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2.10 Featured release
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Added a compilation toggle to remove "register" keyword in API.
Previously commercial, fast_float plug-in is now released as open source under GPL3 license.
MD5 functions are now accesible through plug-in API.
Added support for Visual Studio 2019
Bug fixing.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>