follow comments and add flags in cuda 8.0

cmake/configure.cmake

@@ -60,7 +60,7 @@ else()
         message(FATAL_ERROR "Paddle need cudnn to compile")
     endif()
 
-    set(CUDA_NVCC_FLAGS ${CUDA_NVCC_FLAGS} "-Xcompiler ${SIMD_FLAG}" "--expt-relaxed-constexpr")
+    set(CUDA_NVCC_FLAGS ${CUDA_NVCC_FLAGS} "-Xcompiler ${SIMD_FLAG}")
 
     # Include cuda and cudnn
     include_directories(${CUDNN_INCLUDE_DIR})

cmake/flags.cmake

@@ -195,6 +195,7 @@ endif()
 # Modern gpu architectures: Pascal
 if (CUDA_VERSION VERSION_GREATER "8.0" OR CUDA_VERSION VERSION_EQUAL "8.0")
       list(APPEND __arch_flags " -gencode arch=compute_60,code=sm_60")
+      list(APPEND CUDA_NVCC_FLAGS --expt-relaxed-constexpr)
 endif()
 
 # Custom gpu architecture