[Backport] Need this to build on vs2017

.\src\clparser.cc(56): note: see reference to function template instantiation '_OutIt std::transform<std::_String_iterator<std::_String_val<std::_Simple_types<char>>>,std::_String_iterator<std::_String_val<std::_Simple_types<char>>>,int(__cdecl *)(int)>(_InIt,_InIt,_OutIt,_Fn1)' being compiled
        with
        [
            _OutIt=std::_String_iterator<std::_String_val<std::_Simple_types<char>>>,
            _InIt=std::_String_iterator<std::_String_val<std::_Simple_types<char>>>,
            _Fn1=int (__cdecl *)(int)
        ]
D:\bin\dev\VS\2017\BuildTools\VC\Tools\MSVC\14.10.24911\include\algorithm(946): warning C4244: '=': conversion from 'int' to 'char', possible loss of data

Change-Id: I795a6dbc0b28c7d4367a42d8a8b1ae244ebffe6b
Reviewed-by: Viktor Engelmann <viktor.engelmann@qt.io>
Reviewed-by: Michael Brüning <michael.bruning@qt.io>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>