Subzero: Fix g++ warnings.

src/IceCompileServer.cpp

 //===- subzero/src/IceCompileServer.cpp - Compile server ------------------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
 /// \brief Defines the basic commandline-based compile server.
 ///
 //===----------------------------------------------------------------------===//
 
 #include "IceCompileServer.h"
 
 #include "IceClFlags.h"
 #include "IceClFlagsExtra.h"
 #include "IceELFStreamer.h"
 #include "IceGlobalContext.h"
 
+#ifdef __clang__
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wunused-parameter"
+#endif // __clang__
+
 #include "llvm/Bitcode/NaCl/NaClBitcodeMungeUtils.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/raw_os_ostream.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/StreamingMemoryObject.h"
+
+#ifdef __clang__
 #pragma clang diagnostic pop
+#endif // __clang__
 
 #include <cstdio>
 #include <fstream>
 #include <iostream>
 #include <thread>
 
 namespace Ice {
 
 namespace {
 
@@ skipping 160 matching lines @@
     });
     CompileThread.join();
   } else {
     getCompiler().run(ExtraFlags, *Ctx.get(), std::move(InputStream));
   }
   transferErrorCode(getReturnValue(
       ExtraFlags, static_cast<ErrorCodes>(Ctx->getErrorStatus()->value())));
 }
 
 } // end of namespace Ice