THRIFT-3246 Reduce the number of trivial warnings in Windows C++ CMake builds
Client: cpp
Patch: Ben Craig <bencraig@apache.org>

This closes #553
diff --git a/lib/cpp/test/processor/ServerThread.cpp b/lib/cpp/test/processor/ServerThread.cpp
index 8834269..e9d468f 100644
--- a/lib/cpp/test/processor/ServerThread.cpp
+++ b/lib/cpp/test/processor/ServerThread.cpp
@@ -90,7 +90,7 @@
     try {
       // Try to serve requests
       server_->serve();
-    } catch (const TException& x) {
+    } catch (const TException&) {
       // TNonblockingServer throws a generic TException if it fails to bind.
       // If we get a TException, we'll optimistically assume the bind failed.
       ++port_;