Fix warnings in release build.

This fixes a couple of Clang warnings in release builds of LLVM:

* Missing return in ISelLowering
* Unused variable in NVPTXutil.cpp

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156216 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/NVPTX/NVPTXISelLowering.cpp

@@ -860,7 +860,7 @@ LowerOperation(SDValue Op, SelectionDAG &DAG) const {
     return Op;
   case ISD::CONCAT_VECTORS: return LowerCONCAT_VECTORS(Op, DAG);
   default:
-    assert(0 && "Custom lowering not defined for operation");
+    llvm_unreachable("Custom lowering not defined for operation");
   }
 }
 

lib/Target/NVPTX/NVPTXutil.cpp

@@ -75,6 +75,7 @@ uint64_t encode_leb128(const char *str)
 
   int retval = encode_leb128(temp64.x, &nbytes, encoded, 16);
 
+  (void)retval;
   assert(retval == 0 &&
          "Encoding to leb128 failed");