fix doxygen brief in subzero header files

src/main.cpp

 //===- subzero/src/main.cpp - Entry point for bitcode translation ---------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
-/// This file defines the entry point for translating PNaCl bitcode into native
+/// \brief Defines the entry point for translating PNaCl bitcode into native
 /// code.
 ///
 //===----------------------------------------------------------------------===//
 
 #include "IceBrowserCompileServer.h"
 #include "IceCompiler.h"
 #include "IceCompileServer.h"
 
 int main(int argc, char **argv) {
   // Start file server and "wait" for compile request.
   Ice::Compiler Comp;
 // Can only compile the BrowserCompileServer w/ the NaCl compiler.
 #if PNACL_BROWSER_TRANSLATOR
   // There are no real commandline arguments in the browser case. They are
   // supplied via IPC.
   assert(argc == 1);
   (void)argc;
   (void)argv;
   Ice::BrowserCompileServer Server(Comp);
   Server.run();
   return Server.getErrorCode().value();
 #else  // !PNACL_BROWSER_TRANSLATOR
   Ice::CLCompileServer Server(Comp, argc, argv);
   Server.run();
   return Server.getErrorCode().value();
 #endif // !PNACL_BROWSER_TRANSLATOR
 }