RT: Add a setter for the _cxx attribute in NativeDiosCC.

divine/rt/dios-cc.hpp

@@ -39,6 +39,7 @@ struct NativeDiosCC : cc::Native
     auto link_dios_native( bool cxx );
     std::unique_ptr< llvm::Module > link_bitcode() override;
     void link() override;
+    void set_cxx( bool cxx ) { _cxx = cxx; }
 
     bool _cxx;
 };

tools/divcc.cpp

@@ -31,7 +31,7 @@ int main( int argc, char **argv )
 {
     try {
         rt::NativeDiosCC nativeCC( { argv + 1, argv + argc } );
-        nativeCC._cxx = brick::string::endsWith( argv[0], "divc++" );
+        nativeCC.set_cxx( brick::string::endsWith( argv[0], "divc++" ) );
         auto& po = nativeCC._po;
 
         if ( po.hasHelp || po.hasVersion )