To me it doesn't make sense, but the sample builds because it does not include the header file but only uses extern references and forward declarations.
When you remove both your #include statements your project builds without error - but I couldn't vouch for it to work as intended.
BTW @naveed, didn't I in some other thread point out that Spark.variable("getpos", &bpmm, INT); is deprecated and should now be written as Particle.variable("getpos", bpmm);?