Python: Fix wrapper build on MSVC not having __cplusplus for BitHacks

The `BitHacks.h` header needs the `__cplusplus` define to determine
whether to include `<bit>`. The MSVC compiler only defines this when it
is passed the `/Zc:__cplusplus` flag. The main library was already
setting this flag, but it not set when building the Python wrapper,
causing compilation to fail because `countr_zero` and `popcount` are
being used without `<bit>` being included.

Fixes #612

wrappers/python/CMakeLists.txt

@@ -30,6 +30,10 @@ zxing_add_package(pybind11 pybind11 ${pybind11_git_repo} ${pybind11_git_rev})
 pybind11_add_module(zxingcpp zxing.cpp)
 target_link_libraries(zxingcpp PRIVATE ZXing::ZXing)
 
+if (MSVC)
+    target_compile_options(zxingcpp PRIVATE /Zc:__cplusplus)
+endif()
+
 if (BUILD_READERS AND BUILD_WRITERS)
     add_test(NAME PythonTest COMMAND ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/test.py -v)
     set_property(TEST PythonTest PROPERTY ENVIRONMENT PYTHONPATH=$<TARGET_FILE_DIR:zxingcpp>)