Added nvptx64 target. Things to do:

1. builtins/target-nvptx64.ll to write, now it is just a copy of target-generic-1.ll
2. add __global__ & __device__ scope
2. make code work for a single cuda thread
3. use tasks to work as a block grid and programIndex as laneIdx, programCount as warpSize
4. ... and more...

main.cpp

@@ -262,6 +262,15 @@ int main(int Argc, char *Argv[]) {
     LLVMInitializeARMDisassembler();
     LLVMInitializeARMTargetMC();
 
+    LLVMInitializeNVPTXTargetInfo();
+    LLVMInitializeNVPTXTarget();
+    LLVMInitializeNVPTXAsmPrinter();
+#if 0
+    LLVMInitializeNVPTXAsmParser();
+    LLVMInitializeNVPTXDisassembler();
+#endif
+    LLVMInitializeNVPTXTargetMC();
+
     char *file = NULL;
     const char *headerFileName = NULL;
     const char *outFileName = NULL;