Fix comparison of char and int64 in TestWriteFixNegativeInt

It was broken on clang-ppc64le-linux-lnt bot.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@340517 91177308-0d34-0410-b5e6-96231b3b80d8

unittests/BinaryFormat/MsgPackWriterTest.cpp

@@ -129,7 +129,7 @@ TEST_F(MsgPackWriter, TestWriteFixNegativeInt) {
     MPWriter.write(i);
     std::string Output = OStream.str();
     EXPECT_EQ(Output.size(), 1u);
-    EXPECT_EQ(Output.data()[0], static_cast<int8_t>(i));
+    EXPECT_EQ(static_cast<int8_t>(Output.data()[0]), static_cast<int8_t>(i));
   }
 }