LOGCXX-400: Another case of a build failure because of a narrowing conversion.

https://lists.apache.org/thread.html/c7d3bea60a87b43cb55aae72e78d7044171dec435e2bc75cc0e9c2f5@<dev.logging.apache.org>
diff --git a/src/test/cpp/helpers/transcodertestcase.cpp b/src/test/cpp/helpers/transcodertestcase.cpp
index 6eafc15..cc394f0 100644
--- a/src/test/cpp/helpers/transcodertestcase.cpp
+++ b/src/test/cpp/helpers/transcodertestcase.cpp
@@ -331,7 +331,7 @@
         }
 
         void encodeCharsetName3() {
-            logchar unsupported[] = { 0x1F, 0x7F, 0x80, 0x81, 0x00 };
+            logchar unsupported[] = { 0x1F, 0x7F, static_cast<logchar>(0x80), static_cast<logchar>(0x81), 0x00 };
             std::string encoded(Transcoder::encodeCharsetName(LogString(unsupported)));
             LOGUNIT_ASSERT_EQUAL(std::string("????"), encoded);
         }