fix build with clang

Building CXX object CMakeFiles/antpm.dir/SerialTty.cpp.o
In file included from /home/tade/dev/antpm/src/SerialTty.cpp:13:
In file included from /home/tade/dev/antpm/src/./SerialTty.hpp:15:
In file included from /usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c++/4.7/queue:64:
In file included from /usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c++/4.7/bits/stl_function.h:741:
/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c++/4.7/backward/binders.h:126:16: error: no matching function for call to object of type 'const antpm::contains'
      { return op(value, __x); }
               ^~
/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c++/4.7/bits/stl_algo.h:1176:18: note: in instantiation of member function 'std::binder1st<antpm::contains>::operator()' requested
      here
        if(!bool(__pred(*__first)))
                 ^
/home/tade/dev/antpm/src/SerialTty.cpp:262:25: note: in instantiation of function template specialization 'std::remove_if<__gnu_cxx::__normal_iterator<std::basic_string<char> *,
      std::vector<std::basic_string<char>, std::allocator<std::basic_string<char> > > >, std::binder1st<antpm::contains> >' requested here
    possibleNames.erase(remove_if(possibleNames.begin(),
                        ^
/home/tade/dev/antpm/src/SerialTty.cpp:236:15: note: candidate function not viable: 'this' argument has type 'const antpm::contains', but method is not marked const
  inline bool operator() (vector<string> v, string e) {return find(v.begin(), v.end(), e) != v.end();}
              ^
1 error generated.