Support pre 3.0 cmake versions.
Support pre 3.0 cmake versions.

DavidEichmann/chipmunk-rs,DavidEichmann/chipmunk-rs,DavidEichmann/chipmunk-rs,DavidEichmann/chipmunk-rs,DavidEichmann/chipmunk-rs,DavidEichmann/chipmunk-rs