cppparser: fix compile warnings on MSVC

dtool/src/cppparser/cppExpression.cxx

@@ -81,7 +81,7 @@ as_integer() const {
 
   case RT_pointer:
     // We don't mind if this loses precision.
-    return (int)reinterpret_cast<long>(_u._pointer);
+    return (int)(intptr_t)(_u._pointer);
 
   default:
     cerr << "Invalid type\n";
@@ -104,7 +104,7 @@ as_real() const {
 
   case RT_pointer:
     // We don't mind if this loses precision.
-    return (double)reinterpret_cast<long>(_u._pointer);
+    return (double)(uintptr_t)(_u._pointer);
 
   default:
     cerr << "Invalid type\n";
@@ -120,10 +120,10 @@ void *CPPExpression::Result::
 as_pointer() const {
   switch (_type) {
   case RT_integer:
-    return reinterpret_cast<void*>((long)_u._integer);
+    return (void *)(intptr_t)_u._integer;
 
   case RT_real:
-    return reinterpret_cast<void*>((long)_u._real);
+    return (void *)(uintptr_t)_u._real;
 
   case RT_pointer:
     return _u._pointer;