duplicate global variable looked up by string name

处理方法：

将常量变量的引号去掉：

cudaMemcpyToSymbol("g_fCubeRange",     &_pMCGrid->m_fRange,         sizeof(float));

-->

cudaMemcpyToSymbol(g_fCubeRange,     &_pMCGrid->m_fRange,         sizeof(float));