vtkParseExtras, vtkParsePreprocess: use static storage for returns
GCC 10 warns that pointers to the stack are being returned. Use static storage for this instead. This code is not thread-safe or re-entrant anyways, so this is fine.
GCC 10 warns that pointers to the stack are being returned. Use static storage for this instead. This code is not thread-safe or re-entrant anyways, so this is fine.