Fixed an issue where VS failed to build bladebit due to CJK codepage

[ChiaMineJP]

Building with VisualStudio 2022 with windows system codepage set to cp932(Japanese/SJIS) which is the default codepage for Japanese locale failed due to a bunch of C4819 warnings: Warning C4819: The file contains a character that cannot be represented in the current code page (932). Save the file in Unicode format to prevent data loss I managed to success building by suppressing C4819 warning.