[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>

ninja/configure.py

@@ -302,7 +302,7 @@ if platform.is_msvc():
               '/Zi',  # Create pdb with debug info.
               '/W4',  # Highest warning level.
               '/WX',  # Warnings as errors.
-              '/wd4530', '/wd4100', '/wd4706',
+              '/wd4530', '/wd4100', '/wd4706', '/wd4244',
               '/wd4512', '/wd4800', '/wd4702', '/wd4819',
               # Disable warnings about constant conditional expressions.
               '/wd4127',