Fix VERSION_GREATER_EQUAL for CMAKE < v3.7 (#950)
Fix VERSION_GREATER_EQUAL for CMAKE < v3.7 (#950)

VERSION_GREATER_EQUAL was introduced in CMAKE v3.7.

Co-authored-by: KO Myung-Hun <d809576feff80a0af83d85c9236c767ab77185e8@chollian.net>
FluidSynth/fluidsynth,FluidSynth/fluidsynth,FluidSynth/fluidsynth,FluidSynth/fluidsynth