meson: Set /Zc:__cplusplus for MSVC

Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12881>

meson.build

@@ -1081,6 +1081,7 @@ if cc.get_id() == 'msvc'
                '/wd5105',  # macro expansion producing 'defined' has undefined behavior (winbase.h, need Windows SDK upgrade)
                '/we4020',  # Error when passing the wrong number of parameters
                '/we4024',  # Error when passing different type of parameter
+               '/Zc:__cplusplus', #Set __cplusplus macro to match the /std:c++<version> on the command line
               ]
     if cc.has_argument(a)
       c_args += a