Fixed compilation errors on Windows, plus an error in a test case

platforms/cpu/tests/TestCpuCustomNonbondedForce.cpp

@@ -843,6 +843,10 @@ void testInteractionGroupLongRangeCorrection() {
 
 int main() {
     try {
+        if (!CpuPlatform::isProcessorSupported()) {
+            cout << "CPU is not supported.  Exiting." << endl;
+            return 0;
+        }
         testSimpleExpression();
         testParameters();
         testExclusions();

platforms/reference/include/ReferenceTabulatedFunction.h

@@ -42,7 +42,7 @@ namespace OpenMM {
 /**
  * Given a TabulatedFunction, wrap it in an appropriate subclass of Lepton::CustomFunction.
  */
-extern "C" Lepton::CustomFunction* createReferenceTabulatedFunction(const TabulatedFunction& function);
+extern "C" OPENMM_EXPORT Lepton::CustomFunction* createReferenceTabulatedFunction(const TabulatedFunction& function);
 
 /**
  * This class adapts a Continuous1DFunction into a Lepton::CustomFunction.

platforms/reference/src/ReferenceTabulatedFunction.cpp

@@ -48,7 +48,7 @@ using namespace OpenMM;
 using namespace std;
 using Lepton::CustomFunction;
 
-extern "C" CustomFunction* createReferenceTabulatedFunction(const TabulatedFunction& function) {
+extern "C" OPENMM_EXPORT CustomFunction* createReferenceTabulatedFunction(const TabulatedFunction& function) {
     if (dynamic_cast<const Continuous1DFunction*>(&function) != NULL)
         return new ReferenceContinuous1DFunction(dynamic_cast<const Continuous1DFunction&>(function));
     if (dynamic_cast<const Continuous2DFunction*>(&function) != NULL)