Added missing required kernel names (ApplyConstraintsKernel and...

Added missing required kernel names (ApplyConstraintsKernel and VirtualSitesKernel) to check for platform capabilities, since these kernels are initialized in the next code block.

openmmapi/src/ContextImpl.cpp

@@ -94,6 +94,8 @@ ContextImpl::ContextImpl(Context& owner, const System& system, Integrator& integ
     vector<string> kernelNames;
     kernelNames.push_back(CalcForcesAndEnergyKernel::Name());
     kernelNames.push_back(UpdateStateDataKernel::Name());
+    kernelNames.push_back(ApplyConstraintsKernel::Name());
+    kernelNames.push_back(VirtualSitesKernel::Name());
     for (int i = 0; i < system.getNumForces(); ++i) {
         forceImpls.push_back(system.getForce(i).createImpl());
         map<string, double> forceParameters = forceImpls[forceImpls.size()-1]->getDefaultParameters();