cmake: lower version requirement to common 2.8
cmake: lower version requirement to common 2.8

omf2097/openomf,omf2097/openomf,gdeda/openomf,gdeda/openomf,pmjdebruijn/openomf,gdeda/openomf,pmjdebruijn/openomf,pmjdebruijn/openomf,omf2097/openomf