Avoid C4819 and its disasters

[DuKeM-CSGO]

F:\Github\v8-cmake-master\v8\src\objects\js-temporal-objects.cc(5873,41): error C2065: "temp": undeclared identifier [F:\v8_build\v8_base_without_compiler.vcxproj]
F:\Github\v8-cmake-master\v8\src\objects\js-temporal-objects.cc(5879,62): error C2059: syntax error: ")" [F:\v8_build\v8_base_without_compiler.vcxproj]
F:\Github\v8-cmake-master\v8\src\objects\js-temporal-objects.cc(5880,15): error C2039: "ToHandleChecked": Not the member of "v8::internal::Handle<v8::internal::BigInt>" [F:\v8_build\v8_base_without_compiler.vcxproj]

What's strange is when I open v8_base_without_compiler.vcxproj in VS 2022, the IntelliSense works and doesn't treat them as errors. I don't use code page 65001. Maybe the char ℤ in line 5866 or something else doesn't be read right, I guess.

Originally posted by @DuKeM-CSGO in https://github.com/bnoordhuis/v8-cmake/issues/57#issuecomment-1534918930

May consider adding "/utf-8" to target_compile_option in the CMakelists.txt to avoid this issue, especially when the projects aren't generated in the code page 65001.

[bnoordhuis]

cc @gengjiawen as our resident Windows guru.