Add runnable GPU main-path prototype

AMSS_NCKU_source/ABE.C

@@ -29,16 +29,11 @@ using namespace std;
 #error "not define ABEtype"
 #endif
 
-#if (ABEtype == 0)
-
-#ifdef USE_GPU
-#include "bssn_gpu_class.h"
-#else
-#include "bssn_class.h"
-#endif
-
-#elif (ABEtype == 1)
-#include "bssnEScalar_class.h"
+#if (ABEtype == 0)
+#include "bssn_class.h"
+
+#elif (ABEtype == 1)
+#include "bssnEScalar_class.h"
 
 #elif (ABEtype == 2)
 #include "Z4c_class.h"