imagemagick: build with lcms2 so imagick can do ICC colour management

[redburn]

The imagemagick lib recipe builds ImageMagick without lcms2. The resulting imagick extension cannot read, convert or re-attach ICC colour profiles. Would it be possible to add an lcms2 lib and list it in imagemagick's lib-suggests, passing --with-lcms to ImageMagick's configure when present? Every major distro ImageMagick (Debian, Fedora, Homebrew, official Docker PHP images) already ships with lcms2, would make sense for it to be available here as well.