The attached patch fixes the build with lcms2.

The issue was that configure created variables LCMS_* or LCMS2_* depending on the lcms/lcms2 version, but the Makefile was always expecting LCMS_*. I've fixed it by always setting LCMS_*. This is allowed as per the PKG_CHECK_MODULES documentation (http://www.flameeyes.eu/autotools-mythbuster/pkgconfig/pkg_check_modules...) and keeps the Makefile simple.