currently you can't... cmake build is rigged to work through pkgconfig only; you can find a vst3sdk package on the repos (eg. one of Libraries in https://launchpad.net/~rncbc, if you're on an ubuntu based distro).
sure that,now that you asked, the new way will have that option in the future eg. cmake -DCONFIG_VST3SDK=/path/to/vst3sdk ...
[UPDATE:] maybe now possible in develop branch [7d3602bd]
good catch!
currently you can't... cmake build is rigged to work through pkgconfig only; you can find a vst3sdk package on the repos (eg. one of Libraries in https://launchpad.net/~rncbc, if you're on an ubuntu based distro).
sure that,now that you asked, the new way will have that option in the future eg.
cmake -DCONFIG_VST3SDK=/path/to/vst3sdk ...[UPDATE:] maybe now possible in develop branch [7d3602bd]
cheers