Fix the LCMS handling by the CMake build system.

Added FindLCMS2.cmake from openjpeg.

This problem prevented running the following command:

cmake -G Ninja -DCMAKE_BUILD_TYPE=DebugFull -DENABLE_LCMS=ON -DENABLE_POPPLER=OFF -DCMAKE_INSTALL_PREFIX=/home/shlomif/apps/graphics/inkscape-trunk -DCMAKE_CXX_FLAGS=-fpermissive ../inkscape/