Fix windows arm64 build warnings (treated as error) (#332)

- init.c:24:22: error: unused variable 'vendor'
- init-by-logical-sys-info.c:845:11: error: unused variable 'converted_chars'
- init-by-logical-sys-info.c:754:18: error: comparison of array 'chip_info->uarchs' equal to a null pointer

Author: fbarchard