benchmarks(hybrid_systems/crazyflie/stabilize.drh): add stabilizer.drh
fix(opensmt/egraph/Enode.C): update print_infix func to add parens for
the arg of pow function

CAPD generates a parsing error when it encouters

    x ^ -3

and asks us to provide

    x ^ (-3)
feat(cmake): add gflags and glog as external projects
fix(dsolvers/ode_solver): add debugging message